Why are british indians taller than indians in india?

Hey. I'm originally from india, but me, my parents were born and bred in the UK. I'm 6ft1.5 (187cm) I'm a fairly tall guy. I've mostly had an indian diet, and raised eating indian food, and so have a lot of my friends. But they've all ended up being about 5'9-5'11, average height in the UK. I went on holiday to india, and I realised I was towering over all of the indians there, apart from some pubjabi's who were about 5'9-5'10, I was a couple of inches taller. But the rest were soo small, I attended a wedding, I had to get specially made clothing, because none of the sizes in shops fitted me. I just want to know why are british indians taller than indians living in india? I have a very similar diet in the UK, and I have same genetics. But overall british indians average 5'10, but in india they are like 5'6-5'7? Why is this?