I think it was Harry's bum luck to look more like Dad than Mom.
Dude, that's a really good point, like. Would Snape have plummeted into rageahol if 11-year old Harry showed up with lovely red hair to match his green eyes? Because I think a lot of Snape's trigger had to do with how much Harry looked like James; like Harry was a constant reminder that James got Lily, and not him.
Would Snape have been kinder to Harry is Harry got more of mum's genes? Hmmmmmmmmm! *INTRIGUED*