GRAND RAPIDS, Mich. - A Michigan man whose 13th son was just born says he's convinced that "medically, it's just not possible" for him and his wife to produce a daughter.

He also says it's proving a challenge to agree on a name for their newborn.

advertisement | advertise on newsday

Forty-year-old Jay Schwandt tells The Grand Rapids Press the boy born Wednesday is the second he and wife Kateri have had who arrived with a full head of hair.

The baby and 40-year-old mother are doing well at Mercy Health Saint Mary's Hospital in Grand Rapids. He's 22 inches and weighs 8 pounds, 9 ounces.

The father determines a child's sex. Newcastle University researcher Corry Gellatly's 2008 study says four centuries of genealogical information shows some men may be genetically prone to having more sons or daughters.