By Jan Carabeo

VERONA, N.J. (CBS) — A New Jersey couple is suing a fertility clinic after learning that one of them is not the biological parent of their baby. A judge has ordered the clinic to hand over its sperm donor list because of their case.

“When people ask when she’s right there, what do you say? ‘Oh don’t worry about that, they’re crazy.’ You know she’s gonna ask. How she’s gonna feel? Is she going to disown me? You’re not my dad. You’ve heard that many times. You’re not my dad. I don’t know. I’m afraid of a lot of things, a lot of things,” Drew Wasilewski said.

What should have been a dream come true turned into a nightmare for Wasilewski. He and his now ex-wife had a child through an in vitro fertilization procedure at the RWJ Barnabas Health Institute for Reproductive Medicine and Science.

Years after the daughter was born, the Essex County couple made a startling discovery.

“And it wasn’t until the child was 2 years old that she started having — they’re both Caucasian — she started developing Asian features,” attorney David Mazie said.

The New Jersey couple is now suing the fertility clinic, saying it put the wrong egg with the wrong sperm.

The institute is not commenting on the case citing the litigation.

“Negligence, recklessness, you call what you want, this should never, ever happen,” Mazie said.

According to court documents, Wasilewski found out after conducting a DNA test. He told the mother, “The child isn’t my daughter.”

Confused, she replied, “What are you talking about? How is that possible?” They now want to know the identity of the girl’s biological father.

“They have a right to know who he is,” Mazie said. “They have a right to know his genetic history.”

The child also has a blood disorder that neither Wasilewski nor the mother carries.

The little girl is now 6 years old and her parents have not yet told her the truth.

“In his mind this is his daughter,” Mazie said. “I mean, there’s a lot of emotional distress here.”

Wasilewski says it was the stress of this mix-up that led to his divorce. He also wants to know if more mistakes happened at this institute.

He wants to know what happened to his sperm and whether he may be the biological father of someone else’s child.