PEDIGREES

A Primer

No, pedigrees are not just for lower animals; rather they document a blood line for any individual in question. Pedigrees track blood, yours, your dog's, your horse's, or perhaps just your genes. As you see below a pedigree is produced as a chart. Commercial genealogical programmes all produce various types and styles of charts. Basically, it comes down to ancestors, or descendents, but the amount of information can vary significantly. Family pedigrees show ancestors and focus on locations and identity data, but blood types, data sources, and any significant activity can be included.

MIT chromosome pedigree

 

The MIT chromosome pedigree chart by Professor Brian White shows a typical inter-relationship amongst related elements.[1] Here is a sample human pedigree and one way to analyze it. Use A or a to represent the abnormality if it is dominant or recessive, respectively. Try the possible models one by one.- if the abnormality were Y-linked: Y - normal Y chromosome Y* - Y chromosome carrying abnormality (it doesn't matter if it is dominant or recessive, since males are haploid for the Y chromosome) It would appear only in males, as is observed. However, 1 or 3 would also have to have Y* and be abnormal in order to pass it on to his sons.

This does not fit the data so it is not Y-linked. - if the abnormality were due to a dominant mutation in a gene on an autosome (autosomal dominant): A - dominant abnormal allele a - recessive normal allele
Then either 2, or both 1 and 3 would have to show the abnormality for it to be present in the children. This also does not fit he data."

Genome Research is dependent upon accurate pedigrees for their baseline models as seen to the left below.[2] This is useful data for science, but not really of much interest to genealogists, unless there is some inherited peculiarity in the family worth noting.

American National Health Genome Research Chart

 

While science is interested in aspects of heredity, genealogy is more interested in the legal aspects. Human pedigrees do not differ so much from those shown here and the need for accuracy is just as important. In genealogy we deal with history 'writ small'. We are at the level of the basic building blocks of facts. The courts take great interest in pedigrees for claims of inheritance; and in such claims every relationship must be proved by written records to the court's satisfaction. This rigidity certainly applies in heraldic courts and researchers should bear this in mind and seek to maintain the highest standards of accuracy.

Every source should be double-checked and corroborated (if possible), before accepting data and establishing a new relationship in a family database. So a pedigree is simply a graphic picture of ancestors' names, dates, places and perhaps some interesting comments. These charts are the end products of your genealogical research. Naturally, you can reverse the flow of the chart by indicating descendants from either yourself, or someone else. The process of identifying the details accurately is the same.

The search for relationships is important for a variety of legal reasons, including inheritance and marriage. Biological inheritance is illustrated in the Genome Research chart and law proscribes marriage within a close range of biological relationships. The legal concept relates to the degree of consanguinity, or 'blood' relationship, and is intended to protect society from the effects of in-breeding. Unions between persons biologically related as second cousins or closer are categorized as consanguineous.

The consequence of the legal concern to limit marriage amongst cousins, or closer relatives, is further extended to limiting legal testimony by close relatives, whose objectivity would be in doubt. The same legal concern governs inheritance and many jurisdictions prescribe inheritance rules based on the degree of relationship to someone who dies in testate (without leaving a will of written instructions). Genealogy, and the resulting pedigree, therefore has implications well beyond simple curiosity.

Your Pedigree

 

 

Your own pedigree

 
 

ENDNOTES

1. Professor Brian White, http://web.mit.edu/esgbio/www/mg/pedigrees.html.

2. The National Health Museum, http://www.accessexcellence.org/RC/VL/GG/pedigree.html.

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