Extra toe😱

At my 20w scan today we found out that my baby boy "may have 6 toes on one foot." I've read a bit on this and I'm not too worried. The brain, heart, lungs and spine look great as well as his size.. The only thing that concerns me is we don't have a known family history of this... I do worry it's something i did to cause it? Is it my medication (all said to be OK by Doctor; for asthma) or because I smoked weed BEFORE I got pregnant? I'm just wondering if any of you have dealt with this and what you did after the baby was born?