MSPs have supported a new adoption law for Scotland, allowing unmarried couples, including gay couples, to adopt children.
Mr Peacock said marriage was seen as the best setting to raise a child
Education Minister Peter Peacock said the move could boost the number of homes for children.
At present, only married or single people can adopt. In same-sex and unmarried couples, only one member is seen as the child's legal parent.
The vote have sparked an angry reaction from the Roman Catholic Church.
Joseph Devine, the Bishop of Motherwell, urged MSPs to vote against the move after the Bishops' Conference of Scotland described it as "irresponsible".
However, Mr Peacock defended the change and said it could "significantly" increase the pool of potential adopters.
"That alone could provide more stability and better outcomes for many, many children," he said.
The minister stressed that marriage was still widely recognised as the best setting in which to raise a child.
However, he said: "There is, more than at any other time in modern history, a wide diversity of family arrangements in Scotland."
Mr Peacock also insisted that the Adoption and Children (Scotland) Bill did not give anyone the automatic right to adopt.
He said candidates would still have to be assessed and have their applications approved by a court.
"The most important consideration has to be whether a couple is able to provide a lasting and loving environment in which to raise a particular child," he said.
The Scottish National Party welcomed the broad principles of the bill but claimed the proposals had failed to give children a voice.
Adam Ingram MSP, the party's deputy education spokesman, said: "As the bill stands, only children aged 12 and over will have the right to express their views and be asked for consent to any proposed adoption."
Lord James Douglas Hamilton, the Scottish Conservative education spokesman, said the issue of same-sex couples adopting was a matter of personal convictions and the party was having a free vote on it.
Liberal Democrat MSP Euan Robson said there was nothing in the bill that undermined marriage.
Approximately 400 children a year are adopted and about 6,500 youngsters are currently in the care of local authorities.
MSPs backed the general principles of the bill by 103 votes to eight, with eight abstentions.
The bill now goes on the next stage for detailed amendments.