Allen also had a paper published last year that was similar in purpose to a paper by Loren Marks, another state witness. He argued a large number of studies on gay parenting were flawed, explaining that sampling errors exposed bias.

While his discrepancies with the majority of studies on the subject differed little from the state’s other witnesses, he presented a slightly different perspective than his colleague. Allen said he thought current research presented little if any solid evidence, deeming the scientific consensus “inconclusive.”

“Of the evidence you’ve got, there’s not hard evidence that there’s no difference in child outcomes,” Allen said.

Price had previously said in his personal opinion that a child is best raised in a household with two heterosexual, biologically-related parents.

Allen also authored a paper that examined the high school graduation rates of children from same-sex parents and compared them to their heterosexually-parented counterparts, using 2006 Canadian census data, a country where same-sex marriage has been legal since 2005.

In the study, he said girls in gay households were only 15 percent as likely to graduate as girls with heterosexual parents. Meanwhile, boys in gays households were 61 percent more likely to graduate than their counterparts. 

He said differences in graduation rates between boys and girls refuted the consensus that there was no difference.

“Gender matters,” Allen said. “It shouldn’t matter if household type doesn’t matter.”

During cross-examination, plaintiff’s attorney Kenneth Mogill questioned Allen about his affiliation with conservative groups opposed to same-sex marriage, asking whether he held bias on the issue of same-sex relationships. Allen said he did not.

Mogill asked if Allen believed homosexual acts would result in “eternal separation from God,” in other words, “going to hell.”

“Unrepentant, yes,” Allen said.

Mogill’s questioning marked a common thread between the state’s witnesses, who have all been questioned about their personal beliefs. All of the witnesses for the state have been religious, and some have acknowledged they are, on a personal level, morally opposed to same-sex marriage.

Despite personal beliefs that directly involve the subject of the trial, attorney for the state emphasize their witnesses’ research speaks for itself. 

“His own personal beliefs have no impact on his research or the data it produces,” Michigan Attorney General spokeswoman Joy Yearout said. 

The technicality of the week’s testimony was exemplified during the defense’s redirect examination, when Allen moved to an overhead projector in an attempt to explain the sampling issues he believed were present in Rosenfeld’s and regnerus’ studies, drawing venn diagrams with a marker.

Unlike other states where bans on same-sex marriage are being challenged, Federal Judge Bernard Friedman denied motions from both sides to immediately rule on the case in October, citing factual issues.

This one point of factual contention emerged as the apparent crux of legal arguments in the case, followed by an inordinate amount of testimony from expert witnesses throughout the trial.

Closing arguments will begin Friday at 10 a.m.