When Apple CEO Tim Cook revealed he was gay on Thursday, questions of when other Fortune 500 company CEOs would come out of the closet began to circulate.

The BBC headlined an article following the revelation with the question: Why is Tim Cook the only major gay U.S. CEO?

Well, Cook isn't, but many are clinging to the old habits of a conservative business world. Former BP CEO Lord Browne told BBC that after leaving the company following the discovery of his relationship with a man in 2007. It would be another four years before gay marriage and equal rights for homosexuals would take center stage in the country.

"When I was at university, people who did gay things, homosexual acts, usually went to prison and stayed there a long time," Browne said.

Many of the CEOs of the major U.S. companies grew up in a similar time, and, as a result, became accustomed to continuing to hide their sexual orientation.

Cook delivered a speech in his home state of Alabama this past week, and said that another reason is because in many states, members of the LGBT community can be fired or evicted from their jobs if found out, according to the San Francisco Business Times. He said if powerful business leaders came forward to defend the community it would only benefit the national conversation -- especially at a time when the issue is already in the spotlight.

This, however, may be the exact reason deterring CEOs and business leaders from coming out: because it is a high-profile issue and a part of their lives that is currently private could be forced into the public's view.

An additional burden on the leaders who come out would be having to suddenly become a role model for younger staff, and be knowledgeable about LGBT-specific issues, which may not always be something they know about.

Business leaders also have to think of their careers, especially in a world where global connections are the norm. A number of countries have criminalized the actions and lifestyle of the LGBT community, which could affect future prospects for business leaders.