Up to the second half of the 20th Century Interracial marriages were illegal in many parts of the world including South Africa and some parts of the United States of America. In 1967 the United States Supreme Court decided that laws banning interracial marriage were unconstitutional  so today Americans can contract marriages regardless of race. Protesters of interracial marriage claimed that such a union would lead to Communism, well really? 
Today interracial marriages are legal everywhere or almost everywhere but in some countries people lose civil rights if they marry outside their religion. In the United States interracial marriage is common, Bill de Blasio, mayor of New York City is married to an African-American. There is still racist prejudice against such marriages. If interracial families live in areas where there are many interracial couples and many mixed race people around, the children of interracial marriages shouldn't face big problems.
Reasons for interracial marriage
Being attracted to someone from a different ethnicity or a different community is quite natural and humanity benefits from this as favourable genes are spread between communities and ethnicities that way. .  
- These Two Teens Aren't Just Sisters -- They're Twins This is about two attractive but different looking sisters with interracial parents.