I wouldn't worry too much about the terminology used mate - Gnasher might just be a product of his time and where he's from.
......... I still use the term Half Caste for a person of mixed race. I know it's not strictly PC nowadays but, I don't say it with any malice (where I grew up, I knew a lot of half caste kids). Hell, my Grandad still said Darkie up to the day he died - he didn't mean anything bad by it, that was just his generation.
Don't let it bother you - you've got a missus and a kid. They deserve your energy more than words typed on a forum.