Anonymous wrote:No way. These people are not our family.
Your child's half sibling is a member of your family. You may not know them or have a relationship with them, but they are your child's biological family.
It obviously feels threatening to you. That may be something you want to deal with in therapy so that you don't let your own insecurity hurt this child you have created. You knew going into this that your child would have genetic connections to someone other than you. Acknowledging that your child has biological family that you don't know doesn't have to undermine your bond.
I didn't meet one of my genetic half sisters until I was nearly 50, and she and I are very close. Way closer than a new friend acquired at this age. Our children look so much alike and they have a great cousin relationship. By denying the existence of these kin, you are preventing your child from developing what might be very enriching and positive connections that last a lifetime and beyond, into future generations.