This is not really an area which I'm good at, partly because I'm
not a Tibetan Buddhist, and would like to find out more. I do ask
Origami from time to time about Tibetan Buddhism, but I will try to
explain as much as possible here.
I would say.. the Tibetan Buddhism is quite special as compared to
other streams of Buddhism, as there are some differences to be
noted of, and you need thorough understandings of it before jumping
to any conclusions or slanders. Tantric is one of the paths taught
by Buddha, Buddha has turned the Dharma Wheel thrice: First, is the
expounding of Hinayana teachings. Second, is the expounding of
Mahayana teachings, and finally, the expounding of Tantric
teachings.
The Tantric path seeks to
transform basic human passions of desire and aversion into
spiritual growth and development. Thus, instead of denying primal
sexual and sensual urges as in traditional Buddhism, the practice
of Tantra accepts these urges as sacred life force energy, which is
purified and transformed into wholesome and healthy forces
connecting the individual with higher spiritual awareness. In order
to be successful with Tantric work, one must have skill in both
self-control and acceptance of self and others.
http://www.thewildrose.net/tibetan_buddhism.html
Also, have you realised those tangkas with sexual showings are not
Buddhas?
Only those marked with the 32 Major Marks and 81 Minor Marks are
considered "Buddhas". The rests are the Tibetan-style of deities as
part of the practice, visualisation object, for a vajrayana
practitioner.
No, Shakyamuni Buddha did not have sex even once ever since he has
attained enlightenment. It is important to note that ALL
ARHATS, BUDDHAS HAVE TRANSCENDED WORLDLY DESIRES. It is
clearly stated in the Four Noble Truth expounded by the Buddha soon
after his enlightenment, that Desire Causes
Sufferings, and Buddha have became enlightened and
transcended all his desires. It is in fact that, when Mara
(the evil one, the heavenly devil) who have come to disturb
Buddha's practice of Meditation, that Buddha did not get at all
affected and remained in his meditational concentration. A Buddhist
tantrist, tantric sex practice (doesn't exist in Singapore, I
believe), is totally different from ordinary worldly sex. A Tantric
Practitioner practices without Desire and lust. If he does have
desire and lust, then it would not be "tantric", and will sure to
bring children 
, but not so for those who practiced according to the
tantra.
Anyway, I'm not a Tibetan Buddhist. I'm sure when Origami comes
here, he'll be able to answer your question much better.
