Hi
Do you have any living siblings, or any nephews and nieces? .If you could persuade someone closer than a 1st cousin to test , it would certainly give you the answers to if your father is your bio father.
Having unknown second cousins doesn't mean that your father isn't your father, or all these unknown matches second, and third cousin matches.
If your 1st ( your father's siblings children) cousins have tested and they are not matching to you, I still would not assume that your father isnt your bio father at first glance. It could be that your father was illegitmate ( ie your grandparents are not his bio parents, maybe his bio parents were Irish , or even Scottish even though he was born in England ) .
I'd 100% rule out it first , if it maybe your father that was an illegitmate child.
Does your father have any living siblings? If they do ,maybe they could test?
Regarding the ethnicity bit, I wouldn't totally go by that. Your mother may have a huge bit of Irish in her, being Scottish, and it's not all from your father and vice versa. As you probably know Irish were always popping over to Scotland, and vice versa.
My mother is from Ireland, born and bred , as too my grandparents and my gg and so on. and go back as far as I can possibly trace back in the midst of time, a few centuries, but in my 50% from my mother ( my father is welsh) have lots of scottish in me too with the Irish as well of course ,as many of my lot came over to Ireland from Scotland at one point in time or another , and many of my Irish families also emigrated into Scotland too
I'd be first looking towards any very close family to test, such as your siblings if any , nephews/ nieces, or a living uncle/ aunt. It will make it far easier for you to tell if your father is your bio father or not, or if it's your father 's parents who are the ones that are not the bio parents.
Kind regards
