Y-DNA is passed from father to son virtually unchanged and has the potential to go back thousands of years. The surname then should also be the same (with possible variations of spelling), if other names crop up it could indicate illegitimacy or that the common ancestor was before hereditary surnames were established.
Occasionally when Y-DNA is passed on there are slight mutations which act as markers enabling it to be seen how far back you need to go to find a common ancestor between two males.
Testing for Y-DNA is a brilliant tool for a one-name study and can be used to group people with the same surname into families. There is a Hoyland Y-DNA surname project, which I administer, hosted by familytreedna.com. Only males can take this test as females do not have Y-DNA. If you are a male Hoyland and would be interested to test or would just like to find out more, please let me know.
Occasionally when Y-DNA is passed on there are slight mutations which act as markers enabling it to be seen how far back you need to go to find a common ancestor between two males.
Testing for Y-DNA is a brilliant tool for a one-name study and can be used to group people with the same surname into families. There is a Hoyland Y-DNA surname project, which I administer, hosted by familytreedna.com. Only males can take this test as females do not have Y-DNA. If you are a male Hoyland and would be interested to test or would just like to find out more, please let me know.