How can I get thick hair like Indian ladies?

Oil it every weekend,make sure to massage in the oil,you can get at the indian store. Brush your hair 100 times every night

Like the person before me said, oiling it every weekend is a good idea, to allow the hair to soak up moisture (Key note: this will not thicken hair). However, don't brush it everyday; it's not good for the hair.

The thing is, my parents shaved my head when I was born to ensure the hair grew back thicker (which it did). They did not do so with my sister (she has thin hair).

I'm guessing you don't want to shave your head, so you could try a thickening shampoo and conditioner set.

Your hair is what it is.. it's not going to magically grow thicker, but you can learn to cut and style it appropriately to make it seem thicker. Try getting layers, and embrace what you have! The longer your hair is, the more it will weigh it down.. don't use a flat iron, instead try flipping your head over to blow dry the roots while upside down.. it will help give you some volume and boost at the top.