The stretch marks are not from hormones. They happen when the area the skin covers grows faster than the skin can grow. I had quite a few friends who had this happen, and generally they grew quite suddenly. I never seemed to grow in any noticeable way, which drove me nuts as a kid Because I grew so slowly, I did not get stretch marks. One poor guy I knew, who was the shortest guy in our grade from kdg to the end of grade 6, showed up at school for the beginning of 7th grade as the tallest kid in the class. He grew about ten inches just over the summer. His mom commented that she was glad he was the youngest because he went through all the hand me downs from the next four of his brothers (he had a LOT of brothers and they were all really tall - and never as short as he was until that summer). This kid had stretch marks that showed on his arms, legs, even his neck above his shrt showed them.
A great moisturizer is very helpful with stretch marks. You want something super moisturizing, a cream more than a lotion. Aquaphor is an ointment made from petroleum jelly and chammomile and is incredibly healing, esp to stretch marks. If you try step's cream and can afford it, try using some aquaphor instead of the vaseline. You can also buy plain old refined shea butter from ebay or various online sources and use it straight on the stretch marks. It is the most amazing thing I have used for skin problems. I get it from ebay, just make sure you get REFINED shea that is white or ivory in color. Yes, unrefined has more healing qualities, but the odor is not pleasant at all. I have had great results from refined shea and the unrefined has an odor that can't be hidden or made more pleasant - and it is not just my opinion. People I know who like scented creams and who are more "back to nature" type people than I am have all said the odor is very unpleasant. It can be used just the way it is when it arrives - it just melts into your skin. Or you can melt it in a bowl over a bit of hot (not boiling) water and add other oils or essential oils as desired