The damage is done below where creams can help. BUT creams and lotions make the unpleasant sensation of the skin stretching feel a bit better, so it's worth getting a nice body lotion for those occasions. Some people don't get them though, maybe you'll be lucky? Did you get them during growth spurts in puberty or anything?
I agree that no matter what you use, chances are you will get some. My worst have been top of my thighs with both pregnancies! I use palmers cocoa butter before bed otherwise the stretching feeling wakes me up and I'm only 14 weeks... Makes my stretch marked skin feel lovely and smooth lol
Most of it is just genetics. if your mum has them, you probably will too. I have very tight skin with almost no stretch in it and knew I would get them. I spent a fortune on Bio oil and that Elemis oil that Victoria Beckham used. Still look like I'd been mauled by a tiger. They have faded though.
I got quite a lot in puberty that I can still see, over my thighs, hips and boobs. None at all in either pregnancy though! Seems very random indeed as to whether you'll get them. I'm quite a small person too, so was convinced my belly would succumb. Plus my mum has loads on her stomach - completely covered.
I do think some of it is down to genetics, unfortunately for me. However, just wanted to reassure you that they do fade if you get them. Mine were so angry and red for a period of time and I was horrified, but they have faded loads. Fingers crossed you don't get them, but if you do don't be too alarmed at their first appearance.