Y-DNA

[Prussian]

I undertook a Y (i.e. paternal) DNA 25 marker test sometime ago (Xmas present) to gleam more of my recent ancestry. I am not interested in identifying the geographical origins (‘deep ancestry’) of my direct paternal ancestor thousands of years ago.

The DNA results conflict with the family’s recently acquired photographic and written evidence of around 1865 which, most surprisingly, revealed my paternal MARTIN line is black African. My Y-DNA Haplogroup of Q-M242, sub group Q1a3a-M3 is said to be ‘unusual’ or even ‘rare’ but not black African.

I am the only member of the MARTIN surname Y-DNA project which has a Q Haplogroup. Searches of on-line Y-DNA databases has also be fruitless. It may prove the case that my earliest known ancestor born Magdeburg, Prussia in the late 18th century was the descendant of a slave who took up the surname of his master.

I’m currently trying to encourage a male MARTIN relative to take a Y-DNA test to confirm or otherwise my test results.

Any advice on this genealogical vs genetics puzzle would be appreciated.

[Coromandel]

A few thoughts/theories . . .

Your ancestor could have had African ancestry but not on his father's father's father's (etc.) side of the family
The Y-DNA will only tell you about your ancestor's paternal line, so won't reveal the full picture of his ethnicity. Like all of us, your ancestor would have had eight great-grandparents, who would all have contributed to his overall genetic make-up including his skin colour and other physical characteristics:

Father's father's father [Y-DNA inherited only from this ancestor]
Father's father's mother
Father's mother's father
Father's mother's mother
Mother's father's father
Mother's father's mother
Mother's mother's father
Mother's mother's mother [mitochondrial DNA inherited only from this ancestor]

Seven of the eight of these could have been African without it showing up in the Y-DNA. I believe there are some companies now that do a test that looks at your whole genome and gives you a measure of the ethnicity. Perhaps there will be more clues about the elusive Mr Martin outside of your Y-DNA?

or Your ancestor may have been 'black' but not African
The Y-DNA haplotypes you mention seem to be associated particularly with the Americas - at least that's what I have gathered from a little googling. For example, there are some interesting maps here:

https://www.
genetree.com/q

or Your Y-DNA is not inherited from this man
The most controversial theory, but one that has to be considered: somewhere along the line between him and you, a Martin wife was unfaithful to her husband or the husband knowingly brought up someone else's child as his own (reasons for this could include fostering/adoption as well as adultery). So though there is an apparently unbroken male-to-male inheritance of the surname, there was a "cuckoo in the nest" with someone else's Y-DNA.

[bamagirl]

To add to what Coromandel said, I thought this map and explanation might be pertinent:

https://www.
eupedia.com/europe/origins_haplogroups_europe.shtml#Q

As to the Martin surname, I wonder if someone up the chain on your paternal line had a name similar to Martin that evolved over time and standardized as Martin.

Best wishes,
Barb