Looking for birth sibling born 7/13/1970 in Omaha, NE

My mother and I are searching for the child that she had to give up for adoption before she married my father. We only know a few details because they never let her see the baby (and actually put her under for the delivery). The nurse told her later that it was a boy but they changed so many details to keep my mother from knowing too much that she said it is possible it may have been a girl. Her older brother said the pastor mentioned something about twins even. My mother has never stopped thinking about the baby and I would love to help her find him or her. The details my mother knows for a fact are the baby was born on 7/13/1970 at Clarkson Hospital in Omaha NE. The doctor was Jules Slunicko and it was a private adoption. My mother has blonde hair, green eyes, and is 5'4. The birth father has dark brown hair, brown eyes and is short-average in height. He looked Italian. She said something was mentioned that the adopted family may have lived in Ralston and they possibly had a daughter about 3 years older. If anyone can help me find my sibling I would really appreciate it.