I am 23 with facial PWS (Port Wine Stain birthmark). From what you discribed it sounds like you have PWS. To find out exactly you would have to consult with a Dermatologist in your area. Under resource section at the top you can find a doctor in your area.
As of now what doctors can tell PWS is not gentic. I know a lot of people (guys ang gals) that have several children and only one person (girl) I know has multi children that have some form of a birthmark. I think you are safe on this. Most birth defects in general in think come from the females chromasomes. (Not including birthmarks)
If you would like to see some pictures of my PWS (which is a different color then yours) you can go to my website www.hankspws.com
I hope this helps. If you have any other questions please ask we are here for you. Others should chime in after the holiday.
Have a very marry Christmas.