Background to using DNA

 As a trained scientist I have no difficulty understanding the basics of the science and mathematical statistics underlying genetic genealogy, but I also do not believe in re-inventing the wheel, so I started looking for websites which demonstrated techniques to use. This blog post is a list of the sites I have found most useful and why. This is not intended to be a one-time blog post, but hopefully will grow as I come across more useful sites.

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Diahan Southard's "Your DNA Guide"

 This really set me on the right track in organising my DNA matches, grouping them by "Most Recent Common Ancestor(s)" (MRCA). Yes, I bought the book. If you want to and don't want a solid copy I would suggest purchasing the PDF version from the web site. In particular I would suggest reading the following blog posts on the site:

• DNA Triangulation: explains how to use shared matches (in Ancestry and other sites) to identify MRCAs without ploughing down to segment level,
• What is a Genetic Network: explains the concepts underlying DNA Triangulation

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DNA Painter

 Online visualisation tools for getting your head around your DNA matches (particularly for a very visual person like me). It has tools to help people with recent "non-parental events" locate themselves within a potential family tree and for those people who want to dig down to segment level in their analysis. The section I use most often is:

• The Shared cM Tool: based on the work of a group of genetic statisticians, this allows to isolate the possible relationships a certain level of common cMs can cover.

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The Genetic Genealogist

 One of the pioneers of genetic genealogy (and yes I've purchase one of his books), his blog ranges widely over the uses of DNA in genealogy. He was one of the founders of:

• The Shared cM Project: a statistical analysis of relationships and the variations in shared cM which can occur. This is the data underlying "The Shared cM Tool" (above)

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The Leeds Method

 A method for sorting out your high cM matches into genetic networks, and seeing if you have any recent pedigree collapse. Plenty of explanatory blog posts to help you.

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DNA Explained

 I've only just come across this blog via one of the best coverages of ThruLines^TM I've seen:

• ThruLines Suggests Potential Ancestors – How Accurate Are They?: explains how the "potential ancestors" feature of Ancestry trees is used to create a ThruLine, and how to use these suggestions.

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 That's all for now, folks. Good luck with your DNA matches.

The Parentage of Susan Wood

 My 4xgreat-grandparents, John Dav(e)y & Susan Wood, were married in Laughton on 19 Oct 1807.¹ John had been born in Laughton, but Susan was a "foreigner" from another village.²

Hunting through the indexes, there is only one Susan Wood baptism in the correct era – Susana Wood daughter of Daniel & Elizabeth, was born18th February 1782, her birth being registered by the Wesleyan Great Meeting House in Battle in their non-conformist register in 1789.^3,4,5 However as I've shown in another post, this is not the Susan Wood who married John Davy in Laughton.

The following documentary evidence exists for Susan Dav(e)y nee Wood:

1. Marriage 19 Oct 1807, Laughton (Approximate age 21+) > born before 1786¹
2. Census 6 Jun 1841 Brighton (age 50(-54), born Sussex) > born 1786-91⁶
3. Census 30 Mar 1851 Brighton (age 67 born "Bucksted") > born Mar 1783-Mar 1784⁷
4. Death 7 Aug 1851 Brighton (age 68) > born Aug 1782-Aug 1783⁸
5. Burial 11 Aug 1851 (age 68) > born Aug 1782- Aug 1783⁹

Susan's age is reasonably consistent implying she was born between 1782 and 1786. The change of age between the 1851 Census on 30 Mar 1851 and her death/burial in Aug 1851 (informant was her son William) could mean that she had a birthday between the census and her death.

There is only one source (the 1851 census) which gives a birthplace for her: "Bucksted". This can be identified with Buxted which is quite close to Laughton (the shortest distance between the parish boundaries pre-1844 is about 5 km from Little Streele to Terrible Down).¹⁰ Checking the SFHG index, there is a Wood family producing children in Buxted at this time (Thomas & Sarah) but no baptism for a Susan. The identified children are listed in the table below.^3,11

Child No.	Christening	Died Young?	Next Child	Gap between Baptisms
1	Philadelphia, 20 Jan 1782	No	2 Thomas	21 months
2	Thomas, 16 Oct 1783	No	3 John	33 months
3	John, 30 Jul 1786	No	4 Samuel	16.5 months
4	Samuel, 9 Dec 1787	No	5 Charlotte	22 months
5	Charlotte, 4 Oct 1789	No	6 James	19.5 months
6	James, 25 May 1791	No	7 Charles	17 months
7	Charles, 28 Oct 1792	No	8 Sarah	14.5 months
8	Sarah, 5 Jan 1794	No	9 Lucy	13 months
9	Lucy, 2 Feb 1795, bu 7 Mar 1795	Yes	10 George	27 months
10	George, 5 Jul 1797, bu 15 Jul 1797	Yes	11 George	15 months
11	George, inf bu 20 Oct 1798	Yes	12 Henry	15.5 months
12	Henry, inf bu 9 Feb 1800	Yes	13 Sarah	26 months
13	Sarah, inf bu 20 Jul 1802	Yes	14 Harriet	49 months
14	Harriet, private baptism 30 Aug 1806	No	N/A	N/A

At that time most working class women would breast-feed their children, a practice which resulted in fairly regular gaps between children of about 2 years.¹² One of the causes of short gaps between children is death of a child in infancy. There is no evidence of infant burials for any of the first eight children of Thomas & Sarah. However the next five children, starting with the ninth, all die in infancy, some so soon after birth as to not be baptized. Therefore it makes sense to look at the gaps until the birth of the ninth child (i.e. the first eight gaps) excluding gaps after the infant deaths start. Looking at the offspring of Thomas & Sarah, they are baptising a child approximately every 18 months, but there is a nearly 3-year gap from October 1783 to July 1786. To see if this is enough for an extra child I analysed the gaps between baptisms as follows:

• The average value of the first eight gaps is 19.6 months. 
• If we exclude the 33 month gap, the average of the seven remaining gaps drops to 17.6 months. 
• If we assume that there is an unrecorded baptism during the 33 month gap, then we have nine gaps for an average of 17.4 months between children.

Thus at the average rate for gaps between children borne by Sarah, there is almost certainly enough time for an extra child in the 33 month gap. The fact that this gap overlaps with the inferred range of years for the birth of Susan Wood means there is no familial obstacle to her being the child of Thomas and Sarah.

To conclude, given that Susan Wood was born in Buxted between 1782 and 1786, then there is an opportunity for her to be a child of Thomas and Sarah Wood born about March 1785 (plus or minus a few months). There is weak support for this identification from DNA because my father has a 12cM, single segment match with a descendant of Thomas's sister, Mary.¹³

Sources

1. Marriage of John David Davey and Susan Wood, married 19 October 1807, All Saints Laughton Parish Register, Laughton, Sussex, England, FHL Film 1067216.
2. Baptism of John  Davy, baptised 16 April 1786, All Saints Laughton Parish Register, Laughton, Sussex, England, FHL Film 1067215.
3. Sussex Family History Group, ‘Data Archive on Frontis, Baptism Data’, http://sfhg.frontis.co/bin/index.php, accessed 22 Apr 2021.
4. England & Wales, Non-Conformist and Non-Parochial Registers, 1567-1936, Ancestry.com.au, accessed 31 Oct 2021.
5. Birth Registration entry of Susana Wood, born 18 February 1782, The Great Meeting House, Battle, Sussex, Ancestry.com.au, accessed 23 Oct 2021.
6. Census record for Susan Wood, aged 50, 27 Crescent Cottages, Brighton, Sussex, 1851 England and Wales Census, The National Archives, HO107/1644/244, UK Census Collection, Ancestry.com.au, accessed 11 Feb 2007.
7. Census record for Susanah Wood, aged 67, Crescent Cottages, Brighton, Sussex, 1841 England and Wales Census, The National Archives, HO107/1123/5, UK Census Collection, Ancestry.com.au, accessed 11 Feb 2007.
8. Death certificate of Susannah Davey, died 7 August 1851, registered September quarter 1851, Brighthelmston registration district, General Registry Office, England, vol. 7, p. 203, no. 94.
9. Burial of Susannah Davey, buried 11 Aug 1851, St Nicholas Brighton Parish Register, East Sussex Record Office, PAR 255/1/5/10, East Sussex, England, Church of England Deaths and Burials, 1813-1995,  Ancestry.com.au, accessed 8 Jan 2023.
10. Cockin, T. C. H., The Parish Atlas of England, Malthouse Press, Barlaston, 2017.
11. Sussex Family History Group, ‘Data Archive on Frontis, Burial Data’, http://sfhg.frontis.co/bin/index.php, accessed 22 Apr 2021.
12. World Alliance for Breastfeeding Action, 'Breastfeeding & Birth Spacing', https://waba.org.my/archive/healthcare-research/breastfeeding-birth-spacing/, accessed 8 Jan 2023.
13. Ancestry ThruLines for Alfred Commons (https://www.ancestry.com.au/discoveryui-geneticfamily/thrulines/5C9DF31B-1477-4562-84BC-ED25F3066CCC?filterBy=all).