Just like in many countries, in India there's a national pledge that all schoolchildren are taught. It goes something like this:
India is my country and all Indians are my brothers and sisters....(blah blah blah)... In their well being and prosperity alone, lies my happiness.When I was in school and had to say this every day, I had a problem with the first line. As you can see, if all Indians were my brothers and sisters, then I couldn't marry any of them. Later on, however, I realised that this line is sheer genius. Nehru and gang had figured out that each Indian wanted a lot of kids. This would lead to a population explosion that would outpace any development the country would have. If all Indians truly believed in the pledge, they could only marry non-Indians, resulting in fewer marriages (and probably fewer kids as most of those marriages would long-distance affairs). Also they would have found lots of people from neighbouring countries, resulting in complete peace in South Asia... after all you're not likely to want to fight your uncles and take their land when it would just pass on to you based on inheritance in a few years.
Unfortunately most Indian parents disagreed with this and got their kids married off to their childhood friends' kids, resulting in a population going from 330 million to 1100 million in 60 years. If only our grandparents had followed the national pledge we would be some majorly exotic people who looked like Lisa Ray and probably not be fighting wars all over the place.