>>82168722No one is an aristocrat, so there is no pressure to inbreed for many generations and cause problems. Inbreeding is only an issue if you have bad genes(jew/indian) and/or do it repeatedly.
If a pair of non-brown siblings fell in love and had kids, they'd be fine and be VERY unlikely to then fall in love and inbreeding themselves so it's a non-issue.
That said, OP has nothing to do with breeding.