The issue is the trend of interracial-marriage and what our offspring will look like, the article references marriages for its data on children. It makes the assumptions that the two individuals in the marriage will combine their DNA to produce of child of mixed ethnicity/race.
The Wall Street Journal reported a few years back that 15% of new marriages in 2010 were between individuals of different races. It's unclear whether they've included same-sex unions in the count, but as currently stated, this number is more than double what it was 25 years ago.Why should it make a difference if all things are equal?
What is more antiquated in the though is that children are produced within marriage, from the trends we see that the majority of children WILL NOT being born within marriage by 2050. Actually with declining fertility rates, who knows how many children will be born at all?