I have heard a few stories about the deity brahma and saraswati. I felt disappointed and I hope it is not true.I hope incest is wrong(incest between daughter and father,brother and sister, and mother and son)is strictly against the law of nature and shouldn't be encouraged in any religion.
NO. It does not.
Incest is one of the grave sins in Hinduism.
Here are few verses from the Manu Smriti :
11.58. Carnal intercourse with sisters by the same mother, with (unmarried) maidens, with females of the lowest castes, with the wives of a friend, or of a son, they declare to be equal to the violation of a Guru’s bed
11.170. He who has had sexual intercourse with sisters by the same mother, with the wives of a friend, or of a son, with unmarried maidens, and with females of the lowest castes, shall perform the penance, prescribed for the violation of a Guru’s bed.
11.171. He who has approached the daughter of his father’s sister, (who is almost equal to) a sister, (the daughter) of his mother’s sister, or of his mother’s full brother, shall perform a lunar penance.
And, violation of Guru's bed is one of the mahapatakas or mortal sins in Hinduism as stated in the following verse:
Manu Smriti 9.235. The slayer of a Brahmana, (A twice-born man) who drinks (the spirituous liquor called) Sura, he who steals (the gold of a Brahmana), and he who violates a Guru’s bed, must each and all be considered as men who committed mortal sins (mahapataka).
And here a few verses from the Parashara Smriti's chapter 10:
If a person, bereft of all sense, cohabits with his mother, or sister, or self-begotten daughter, he must perform a three-fold Krichchhra penance ; a tire-fold Chandrayana should also be performed ; he must, likewise, cut off his male organ.
On cohabitation with a mother's sister, it is requisite to cut off the male organ ; but if it has been done unwittingly, the sinner must perform a double Chandrayana. He must give ten couples of cattle, each couple to consist of a female and a male, as fee : this is the expiation as declared by Parasara.
On sexual union with a father's wife, or a near relative of the mother, or a brother's daughter, or the preceptor's wife, a son's wife, or the wife of a brother, or the wife of a brother of the mother, or any woman of the same gotra, a three-fold Prajapatya is the expiation prescribed ; a couple of cattle is the fee to be given. Thus the sinner undoubtedly gets rid of his sin.
So, as you can see, such sins are quite grave and the expiation measures are quite severe too.