Well, I'll give you some educated information. Yes, your stretch marks have a lot to do with genes, and like I've argued with an ignorant friend of mine who seriosly likes to believe what she hears... is that no, you cannot prevent them. You can however help them be less irritating and apply some belly balm to help your skin stretch easier and be less severe, however, those women who don't have stretch marks and who tell stories about how they used cocoa butter everyday just happen to be lucky, but on the other end of the spectrum, there are those women like me who do apply the appropriate belly balm every day, and still get the.
It depends on how fast your baby grows, how much weight you gain and so forth. I got them on my belly, but even worse on my hips and even on my back where it meets my bottom because I put on a lot of weight in those areas. Not to mention the baby tummy, that saggy sack of skin just just sort of hangs there and makes you look pregnant even after you have your kids. Maybe you'll be lucky and will still look pretty good afterwards. I have that saggy belly thing going. I will say that stretch marks fade and shrink. My stretchmarks were hardly noticeable a couple years after I had my first. Anyways, I know this may be the good news you don't want to hear, but educated at that. I'll just tell you this. After I had my first baby and stepped on the scale and saw the huge amount of weight I accumulated, how unattractive my chest looked (because your nipples get real dark and the boobs get splotchy) and having a saggy sack of skin and newly acquired scar and shrugged it off and said "these are battle wounds, my son is worth it all". Now that I'm pregnant with my third and already putting the pounds on as I swore I wouldn't, I find myself coming to peace with my body, the weight I am and will gain, and the possible fact that I just won't be as attractive afterwards, because life is much more about looks. Though we do care. What is important is that your husband loves you and will still be there for you, faithful, and with love even when you fall out of competetion with the younger, more fit girls (I'm 27, nearing 28 and I'm coming to terms with leaving my youth, no longer one of those young girls). He really does love me, and I have a family, and although I personally do care about my weight, body and figure, I also know that some things are out of control, whether literal or because for some reason I just don't have the means to control them myself. Anyways, I hope this long winded response leaves you blessed.
HB