Yesterday, the Boy Scouts of America voted to finally allow openly gay scouts to be members. It did not vote on, and so retained, a ban on openly gay scout leaders, meaning that gay scouts will have no choice but to leave when they turn 18. This is a thing which happened in the year 2013.
The approximate 1,400 voting members of the Boy Scouts of America's National Council approved a resolution to remove the restriction denying membership to youth on the basis of sexual orientation alone. The resolution also reinforces that Scouting is a youth program, and any sexual conduct, whether heterosexual or homosexual, by youth of Scouting age is contrary to the virtues of Scouting.
Boy Scouts of America is a fiercely conservative organisation, retaining a ban on members who are atheist or agnostic (citing the oath that scouts swear to do their "duty to god"), and many members haven't taken well to the news that gay boys can be scouts from the year 2014. The New York Times speaks to one :
Allison Mackey of Hanover, Pa., has five sons — one an Eagle Scout, three now active in scouting and an 8-year-old who had planned to join.
The family has discussed the issue and reached a decision, she said: All the sons were willing to abandon the Boy Scouts if openly gay members are allowed.
“The Boy Scouts are something we’ve really enjoyed because they celebrate manliness and leadership,” she said. But, she added, she and her husband were “looking to encourage our sons in traditional Christian values.”
One commonly-cited reason for the continued existence of the policy is the strong links between Boy Scouts of America and the Mormon church. The church, which the AP reports  has more scouting troops than any other religious denomination in America, teaches that same-sex relationships are sinful, and fiercely opposes policies like same-sex marriage. But it has recently eased its attitude towards its gay and lesbian members, advocating a "hate the sin, love the sinner" approach. Mormons are still expected to refrain from homosexual sex, however, and so gay and lesbian mormons are expected to be celibate.
In the end, the support of the Mormon church for the rule change – while emphasising that all sexual activity on the part of scouts goes against expected standards of behaviour  – was probably a large chunk of the reason it went ahead. In the year 2013.