http://navy.army.com/info/join/medical

Just a few of the highlights which could be extrapolated to exclude "them".

Hermaphroditism (state characterized by presence of both male and female sex
organs).

Psychiatric Conditions: Schizophrenia. (For the previously disqualifying disorders of: Major depression, recurrent; Bipolar disorder; Panic disorders; Sexual disorders; and Personality disorders, severe; recommend courtesy review first, but NRD can request MEPS exam. MEPS examiner usually will decline and instruct that courtesy review be requested first.

Undescended testicle unless surgically removed or confirmed to be absent; congenital or surgical bilateral absence.

Substance dependence.

Anabolic Steroid Use. Any applicant admitting steroid use within the previous 2 months is not enlistment eligible. The Chief Medical Officer at MEPS may consider waivers on an individual case basis after attaining internal medicine consultation or appropriate history. If a waiver is recommended, request must be forwarded to CHBUMED (Code 25) via CNRC (334). Send the following test results for waiver consideration: (1) microscopic urinalysis and (2) liver function study. Dosage strength of steroids used must also be documented. Use of steroids longer than 2 months before applying for enlistment is not medically disqualifying; however, any indication of high steroid dosage and/or chronic use must have internal medicine consultation to evaluate late or residual steroid effects.

And a few that I would be suspect of:

Addiction to drugs.

Acquired Immune Deficiency Syndrome (AIDS), AIDS Related Complex (ARC),
HIV antibody, or history of any of the above.

Body mutilation, piercing, branding/intentional scarring that are excessive or
eccentric are disqualifying. Some examples are:
A split or forked tongue. This is a surgical procedure done to make the tongue
appear serpent-like;
foreign objects inserted under the skin that creates a design or pattern;
enlarged or stretched-out holes in the ears (other than a normal piercing) This
typically occurs when rings of a progressively larger size are inserted in the
ear lobe. After time the hole is expanded. Any occurrence of this type is
considered faddish and therefore disqualifying. All questionable cases will be
referred to the appropriate Region Commander for final disposition.
Gold veneers on the teeth or any type of dental ornamentation are also
disqualifying.
branding/intentional scarring that appears on the neck, face or scalp is
disqualifying. All brandings/scarring that are offensive in nature, excessive or
eccentric are also disqualifying. All questionable cases will be referred to the
appropriate Region Commander for disposition.

Cirrhosis.

Idiocy (extreme mental deficiency).

Imbecility (feebleness of mind).

Neurosyphilis of any form (syphilis of central nervous system).

Silastic Implants (except breast).

NRA Life Member