Need reassurance please...

I've got one son (first ever pregnancy), I'm pregnant with my second only 8 weeks but my mum and nan just told me they both lost their second babies at 4 months so now I'm super scared that it'll happen to me! They don't know I'm pregnant as I'm not telling anyone yet. I've been quiet lucky fell pregnant very quickly and had no complications just yet (touch wood) do you think there might be a genetic link to miscarriages and think there's a higher chance of me misscarring later on (at 4 months) when my parent/nan did?