Hello,
My father had black hair and very dark brown eyes and so do / did some of his relatives. I'd assumed that those features came from the Irish genes, which I have found further back. Some Irish people have reddish hair but black hair and dark eyes are also Celtic (Irish and Welsh).

However, I have also looked through Liverpool Parish registers for one line of my Manx family who moved to the Island from there and noticed quite a few people who were noted as being black (although another unmentionable word was sometimes used), in the late 17th / early 18th Centuries. Presumably these people came over on the ships used for slavery and settled in Liverpool, but as there was much too-ing and fro-ing between L'pool and the IoM, and, I believe, that the ships would sometimes dock on the island en route, this would be the most obvious connection and the way for people of African descent to arrive in the Island.

Jo