Dr. Alfred Kinsey's 1948 blockbuster Sexual Behavior in the Human Male was followed on September 14, 1953 by (duh) Sexual Behavior in the Human Female. It cost $8. Everyone claims they read it for the articles.
More than 5,500 women were interviewed, and they spoke liberally about sex, with partners and without, how many, where and at what time, if keeping your feet on the floor counts, and there was even the rumor of female orgasm.
We can now say with absolute certainty that these things are true:
7% of single women aged 20–35 and 4% of previously married females aged 20–35 are totally bi.Or so it was true in the 1950s.
2 - 6% of females, aged 20–35, are pretty gay.
1 to 3% of unmarried females aged 20–35 are complete lesbians.
Married women do it 2.8 times a week in the late teens, 2.2 times a week by age 30, and once a week by age 50. Women over 50 were apparently not asked.
26% of all married women reported having had at least one extra-marital affair before the age of 40. Women over 40 were apparently not asked.
12% of all women like the rough stuff.
The fact is, this information came at a point in American history we generally think of repressed and conservative and that we are so much more open-minded about sexuality, and homosexuality in particular, than sixty years ago.
The logic went something like this: Because Communism is the opposite of America, and homosexuality is the opposite of America (because God hates ... well, you've been told who God hates) therefore homosexuality is Communism.
Like that joke about God being Ray Charles. But seriously.
So let's say there is someone in the State Department who has a secret homosexual life. Either a) they are a Communist spy or b) even if they aren't they are susceptible to blackmail in a way a straight person isn't so they may as well be a Communist spy, they will betray us eventually.
In other words, the bigotry inherent in an intolerant society can be used against you before the fact because straight-hate makes you untrustworthy.
Shorter answer; Being gay doesn't make a gay person a bad person. Being straight makes a gay person a bad person.