NEW YORK — The president of the leading Southern Baptist seminary has incurred sharp attacks from both the left and right by suggesting that a biological basis for homosexuality may be proven, and that prenatal treatment to reverse gay orientation would be biblically justified.

The Rev. R. Albert Mohler Jr., one of the country's pre-eminent evangelical leaders, acknowledged that he irked many fellow conservatives with an article earlier this month saying scientific research "points to some level of biological causation" for homosexuality.

Proof of a biological basis would challenge the belief of many conservative Christians that homosexuality, viewed as sinful, is a choice that can be overcome through prayer and counseling.

However, Mohler, president of the Southern Baptist Theological Seminary in Louisville, Ky., was assailed even more harshly by gay-rights supporters. They were upset by his assertion that homosexuality would remain a sin even if it were biologically based, and by his support for possible medical treatment that could switch an unborn gay baby's sexual orientation to heterosexual.

The March 2 article on his Web site was titled: "Is Your Baby Gay? What If You Could Know? What If You Could Do Something About It?" He began by summarizing recent research into sexual orientation, and advising his Christian readership that they should brace for the possibility that a biological basis for homosexuality may be proven.

Paul Myers, a University of Minnesota biology professor who critiqued Mohler's column, contends that there could be many genes contributing to sexual orientation and that medical attempts to alter it could be risky.