The executive director of a Christian anti-gay group in the US has referred to a study which claimed that children of gay parents were worse off than those with straight parents, and quoted scripture which read that those doubting God should be “cast into the sea”.

Writing on his Facebook page, David E Smith, the director of the Illinois Family Institute, wrote a reference to a study published last year which claimed that children born in the twentieth century to parents who had a gay relationship have encountered more personal problems in adult life than those born to married, straight parents.

The population-based survey, written by Professor Mark Regnerus, was published in July’s Social Science Research, and was the largest of its kind, the University of Texas said, to feature children with gay parents in such a broad, probability-sampled population.

Engaged in a debate around same-sex parenting on his Facebook page, Mr Smith wrote: “Have either of you read the the Regnerus study on family structure? I think you need to before suggesting that it would be okay to place children in homosexual homes.”

He then quoted a passage from the Bible which suggested that those doubting God should be killed.

He wrote: “‘And whosoever shall offend one of these little ones that believe in me, it is better for him that a millstone were hanged about his neck, and he were cast into the sea.’ ~Mark 9:42″

The organisation, Minnesota for Marriage, which was funded by the National Organisation of Marriage, an anti marriage equality group set up to push Proposition 8, released a video last year which cited the research, and it was used as a focal point of its campaign against equal marriage. 

The Regnerus study came under fire for introducing sexual orientation into what was seen as more of a comparison between children in unstable parenting environments with those in environments with stable, married parents.