Here is a link to a recent article by Silvia Jadur and colleages:
Children Born by Assisted Fertilization: Information on the Procreative Origin
The present paper briefly reviews some aspects that affect people with infertility problems and children born through assisted reproduction. Making a decision to have a child and accept medical help represents an important moment in the life of a couple. All parents are confronted at some point, with the questions, that every child asks, that is “How was I born?” All children need to know their history of origin. However, most parents are not comfortable providing the answer. In case of parents, who resorted to reproductive medicine, the answer requires a particular approach mainly because it often revives painful and unresolved internal conflicts. Another problem is that the parents do not feel comfortable to talk about the fact that medical help was required to conceive their child and that the medical intervention sometimes required the donation of gametes (eggs or sperm), or simply do not know how to talk to children about this issue. However, the children have right to know their origin. Our experience indicates that some children with behavioral problems improved significantly after the family spoke openly about their origin. Children need to be told the truth. We cannot lie to them nor remain silent.