Children raised by gay and lesbian couples develop just as well as those brought up by traditional couples, a British child psychologist on Friday told a U.S. federal court considering whether a California ban on gay marriage denies constitutional rights.

Lawyer David Thompson, defending the ban, jousted with Michael Lamb, head of the Social and Developmental Psychology Department at Cambridge University, about whether a child growing up without a father or without a mother would face developmental problems.

Two gay men and two lesbian women are asking the federal court to rule the right to marry has no exceptions under the U.S. Constitution, a fight they hope to take all the way to the U.S. Supreme Court in a bid to overturn bans on same-sex marriage in 40 states.

Read the rest of Peter Henderson’s Reuters article here.