Heterosexual is a noun describing a person with a heterosexual sexual orientation.
There are a 4 sexual orientations : Heterosexual, Homosexual, Bisexual and Asexual.
Heterosexuals is a sexual minority! Bisexuals are the majority and seems to be the normal human sexual orientation. Homosexuals is another sexual minority.
The kinsey Scale is probably the best graphic depiction of the different sexual orientations:
(notice it does not include Asexuals).
When we talk about sexual orientation 3 factors seems to determine what sexual orientation a person has:
1) Attractions
2) Behavior
3) (Self) identification
So to answer your question:
A heterosexual is a person who is exclusive physically, emotionally and romantically attracted to persons of the opposite sex. A heterosexual only has sex with someone of the opposite sex. The person identify him/her-self as heterosexual.
A homosexual is a person who is exclusive physically, emotionally and romantically attracted to persons of the same sex. A homosexual only has sex with someone of the same. The person identify him/her-self as homosexual.
Bi-sexual is person who is either physically and/or emotionally and/or romantically attracted to persons of both sexes. A Bi-sexual can have sex with a person of the same sex or a person of the opposite sex. The person or others identify the person as heterosexual, homosexual or bisexual.
Asexual is a persons who is not attracted to either of the 2 sexes. The person does not have sex.
The reason why most people think that heterosexuals are the majority and normal is that the majority identify themselves as heterosexual. But a person who selfidentify as heterosexual may have had sexual experiences with someone of the same sex (behavior) or may be attracted to persons of the same sex but do not act on these atttractions for various reasons. But per definition it is false that hetersexuality is the norm. Exclusive heteroseuxality is not normal.
Again per definition the majority are bisexuals. Many people have (attractions to some of the same sex whether they act on these attractions or not) or sexual experiences (behavior) with someone of the same sex. The person may identify him/herself as either heterosexual or homosexual but is per definition bisexual, if the first 2 factors are present (Attractions and behavior).
Homosexuals are a smaller sexual minority than heterosexuals. Per definition it is not normal to be exclusively homosexual or exclusively heterosexual. Whether it is natural to be homosexual, since it is not normal, is another question. Much scientific evidence points to natural factors influencing sexual orientation. But no single factor has yet to be proved to cause homosexuality or heterosexuality for that matter.
Some homosexuals deny or conceal all 3 factors determining sexual orientations. Many homosexuals live in the socalled "Closet". They may even marry someone of the opposite sex and have children and show a large degree of heterosexual functioning.
Some exclusively heterosexuals may also have sex with some of the same sex (in exclusive same sex enviorments like the army or in prisons.
It is human nature to want to label everything - to organize the perception of the world outside and inside. Some shun labels and a new label for those are POMOSEXUALS;
http://anonym.to? http://en.wikipedia.org/wiki/Pomosexual