My ds#1 is a child i had with my ex, but i only see him as a sperm donor. i have been with DH since my son was 9 months old, and we now have 2 children together. Since day one of our relationship, DH has seen him as nothing but his son, and treats all kids the same. They have a special bond (they go to watch the Western Bulldogs play, they are members of the cheersquad) and i think its great.

Its ultimately up to you, but i know i would have loved to be a twin when i was younger...