Reincarnation is Supernatural
It certainly doesn't seem to be consistent with the modern scientific worldview. A number of Buddhist modernists have questioned or reinterpreted the idea of reincarnation in order to render it more scientific. An example of that tendency is Buddhadasa, whose ideas are very influential (and rather controversial) in Thailand.
Belief in souls that reincarnate wasn't unknown among the ancient Greeks. Orphism taught a doctrine interestingly similar to that of the Indian Jains and a number of famous Greek philosophers including Pythagoras and Plato were influenced by it and stoutly championed the idea of reincarnation.
In Buddhism, reincarnation has always had kind of an uncomfortable relationship with the anatman (no-self) doctrine that basically denies the existence of a human soul. The philosophically astute Indo-Greek king Menander is depicted as inquiring into that point in the ancient 'Milindapanha', a famous Buddhist dialogue. If there's no soul, transcendental-self or jiva that takes on a new body upon rebirth, then what is it that reincarnates? The Buddhist monk Nagasena explains that nothing substantial passes from one life to the next, but nevertheless there's dependent origination, or as we might say causal connection, between them. His analogy was lighting one flame from another.
you have "Buddha", its posted in the religion Forum...it's a religion.
Our Western idea of 'religion' is a product of the Judeo-Christian-Islamic environment in which Western civilization developed, and it doesn't apply precisely to Asian traditions like Buddhism and Confucianism. These Asian traditions kind of overlap with our Western idea of religion, sharing many characteristics with it. There's salvation, heavens, temples, monks, scriptures, incense and pilgrimage. But at the same time, they manage to differ in ways that Westerners would probably consider essential. In Buddhism there's no God, little emphasis on faith, and there's no divine law or supernatural revelation.
As Bluecrux said in the first post, the Buddha told his inquirers not to believe blindly in anything (even him), but to go and experience things for themselves. Historically, human nature being what it is, Buddhists haven't always lived up to that and there's lots of adhering to tradition simply because it's tradition and to scriptures just because they are scriptures.
Is there no supreme being pulling the strings in it?
Nope. There's no creator-god or monotheist king-of-the-sky. Traditional Buddhists in ancient times didn't deny the existence of gods exactly. But whatever gods might exist were simply conceived as natural beings, residents of higher and more refined but still natural planes of being. When it comes to Buddhism's purpose of eliminating dukkha, the gods are kind of irrelevant. They need enlightenment too, just like humans do. And since gods in their lush heavens are more tempted by pleasure and by power than we are, they might actually find enlightenment more difficult to achieve. There's an extraordinary humanistic idea in Buddhism that in some ways it's better to be a human being than to be a god.