I don't mind if it's parents. I was nearly born in Ireland because my dad was going to be in Germany for my birth, and my mum wanted to be with her family for it, but my dad insisted I stayed with his family in Aberdeen instead. But I probably would have still considered myself Scottish.
Grandparents rule takes the piss. No-one ever really has an affiliation towards their grandparents nationality.
So what about for example if mcburnie had kids in England but he plays for Scotland and see's himself as Scottish. He then raises his kids and they become class footballers but we should turn them away because he only technically qualifies through his grandparents.