Andreewogff perhaps... but given most of the father's family have traditionally emigrated to the States(for as many generations as we could track) in order to avoid working in England for the English.... its pretty unlikely.
To put it in context when my father went to stay with american relations as a young man, to work on a j1 for the summer. They were outraged to hear he wasn't an active member of the IRA at the time. The same people continued to financially support their cause for as long as they lived. They would have happily shot a british soldier in the head given the chance and seen it as something to be proud of. I'd imagine a family member turning "to the tans" would be considered quite the traitor in their eyes..given some of their parents stories of negative interactions with british soldiers I can see why they would have learned to hate that way....living away also allowed them to be more extreme in their views. Its easier to dehumanise people if your not in contact with them.
My father for the record had no interest in terrorism or the IRA activities but historically that was the way the family politics leaned. Perhaps on my mothers side though. They were a little more mellow about politics, but theres no stories of them if it happened(unlike the multiple missionary priests) In both families it's quite likely would have been shunned when they came back from war if they had fought for the British. Sad but true.
The difference is for me a family member being in the british army wouldn't be something to be proud of and would never be considered something to celebrate. Pitied perhaps but not celebrated.
I think people can sometimes underestimate the degree anti imperial sentiment that can still exist within Ireland,we joke about it...800 year of oppression etc but theres a strong undercurrent still present.The Republic of Ireland has only been a independent country for less then 100 years, Its not that long ago since the British army were an occupying force here.
I don't there is any glory involved in violence on either side though and I believe things have moved on over the last generations or two thankfully....but I still stand by the fact its a personal choice not to wear the poppy.