It can't all be down to genetics, my mum is 5'5 (size 5 shoes), my dad was 5'9 (size 9 shoes) and yet I'm 6'1 and have size 12/13 shoes...
And no I'm not the milkman's
The only thing different is at the age of 11 we realised I was lactose and gluten intolerant so I cut all dairy out of my diet, I replaced this with soya alternatives until I was 23.