Seeking Your Y-DNA

There has been a discussion that both Y-DNA and surnames are handed down from father to son. This of course is true if the surname is transmitted to the male heirs at the same time the Y-DNA. However, this had not always been the case. The figure to the right shows such a period in Welsh and English history were a surname was transmitted due to changes in the "law of the land". Here, prior to 1536, very few carried the surname JONES. In a fairly brief period, there appears a large number who took this surname. This "cohort" effect, produced a large number of JONES families who did not share the same Y-DNA. In fact, it was more likely that other surnames shared the same Y-DNA due to the fact that the Welsh naming system did not use an English surname. Since the change in Welsh law became English law, the English system of naming [first name, surname] was required of all Welsh who were to participate in this new system. [Act of Union, 1536]

The diagram to the right shows how the Welsh Y-DNA was transmitted to male heirs. [All males had equal inheritance under Welsh law.] Four male children of Thomas, 1) Richard ap Thomas, 2) Edward ap Thomas, 3) John ap Thomas, and 4) David ap Thomas would receive the same Y-DNA from Thomas.


Their children, 1) Peter ap Richard ap Thomas, 2) David ap Edward ap Thomas, 3) Thomas ap John ap Thomas, and 4) John ap David ap Thomas, would also share the same Y-DNA. During, and after the Act of Union, their children would be given [if they did not choose] a name under the English system. Thus, 1) Peter ap Richard ap Thomas, could become Peter Richards, 2) David ap Edward ap Thomas, could become David Edward(s), 3) Thomas ap John ap Thomas, could become Thomas Jones, and 4) John ap David ap Thomas, could become John David. Four different surnames, but all share the same Y-DNA. Multiple names, becoming multiple surnames, all under a new legal system.

When your family tree reaches this time period, you will need to take these factors into consideration. You will need to shift your tree climbing to a Welsh system of names when you seek your Y-DNA.

Research taken from: The Jones Genealogist, Vol.VI, No.4, Nov/Dec, 1994.