How many out there have heard others say "I am 1/2 Eberhardt or I am 1/4 Eberhardt" (you can fill in any surname in place of Eberhardt)?  Probably all of you have heard this, but how much Eberhardt are you - really?

The study of genealogy for me has been and still is an amusing adventure.  I prefer to view it as being similar to piecing together a jigsaw puzzle.  Most often you start with very few pieces (if any) and eventually with time,  you find all the pieces and are able to complete the puzzle.  It should be viewed as no more than a mental task.  It is a mental task that I have enjoyed being engaged in over the years.

Having been trained as a biologist, I have a unique advantage in being able to answer this question.  The answer, biologically/genetically speaking, is quite simple. Each of us (genetically speaking) is very little Eberhardt - even if we carry the surname.  I hate to disappoint anyone out there, but it's time for a reality check and perhaps a little biology lesson.

Individual humans generally differ about .1% genetically (one tenth of one percent). This 99.9 % genetic similarity is what makes us humans. What makes individual humans appear different is how those genes are expressed or our genetic phenotypes.

Each of us has 46 chromosomes in each and every cell of our body.  Half of these chromosomes came from each of our parents.  During the process of meiosis, these 46 chromosomes pair up to make 23 pairs of homologous chromosomes.  These pairs then divide during the formation of our gametes (egg cells and sperm cells).  Which chromosomes go into each individual gamete is completely random.  The end result is that each egg cell or each sperm cell will have 23 chromosomes.  During fertilization, the number is then returned to 46 chromosomes or 23 pairs of homologous chromosomes.  Then before the fertilized cell divides into two cells, the chromosomes are duplicated so each new cell has 46 chromosomes.  This process of cell division is called mitosis.

With that said, one has to reflect on the numbers of individuals that have contributed the chromosomes in the past.  Our genetic code is found on the chromosomes.  Each of us has four grandparents, eight great grandparents, sixteen great great grandparents, etc. etc.  The number increases by a factor of two for each generation you go back in time.  The further you go back in time, the more genetic ancestors you have - the more contributors to your individual genetic "pool".

Some of us might carry the Eberhardt name but in reality, we are merely a random blend of the chromosomes/genes of those that came before us.  We may have the Eberhardt name, but in reality have had a forever changing combination of genes (and gene expression) over the many generations.
  
There is one pair of chromosomes that is of particular interest to the genealogist.  This pair would be the sex chromosomes.  Females have two "X" chromosomes - one "X" from each parent.  Males have an "X" and a "Y" chromosome.  The "X" comes from the mother and the "Y" comes from the father.

It so happens that long ago, when family surnames were first being used in Europe, the family surname came from the male parent.  Little did they know, way back then, that the "Y" chromosome was also passed down from the male parent to male offspring.  They "Y" chromosome is the only chromosome that has been passed from one generation to the next with a predictable pattern (always father to sons).

In the case of females, you know an "X" has come from the father - but your father's "X" came from his mother.  The "X" you received from your mother could have come from either her mother or her father.

This is why Y-DNA testing has been helpful to the study of genealogy.  The results help you to trace the family surname back into time.  The "Y" chromosome is passed on unchanged for many generations.  Over thousands of years there have been a few mutations to the genetic code in the Y chromosome.  These mutations account for the different Haplogroups that exist worldwide. 

Each surname (if the surname has been around a good long while) will most likely have several Y-DNA lines.  In theory, all Y-DNA for a particular surname should be the same if passed from father to sons from his father, etc.  However, due to adoptions and surnames being passed from female parent to male children instead of using the surname from the male biological parent, multiple Y-DNA lines now exist for each surname.

To bring some closure to this essay ... Genealogy should only be viewed only as the search for the origins of a surname and the search for relationships between individuals that may share a particular surname through the study of their lineages.  Y-DNA testing can assist with that search.  Genealogy should not be used in an effort to assume or conclude the genetic similarity between two distant individuals that have the same surname.

Ray Haupt - Aug. 2009
(mother's maiden name is Everhart)
How much Eberhardt, Eberhard, Everhart are You?
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