According to my mother, when she was of courting age, you aren't allowed to marry someone else of a different dialect group!! If you're are Teochew, your only choice of a spouse was a Teochew. A spouse of cantonese, hakka is a no-no. Another race? No chance. Now in my generation, I have cousins who have married spouses of different skin colour, different nationality, even different religion. Society isn't going back to the old ways. In current times, skin colour is no longer the consideration. It's his/her ability to bring back a decent paycheck, all other things being equal.
Cheers!