In islam cousin marriage is permissible, 33:50, 4:23, there is no divine punition for having sex with your sister, Umdo12.3, God in the Bible seems to condone that kind of behavior, Gen38:15, Gen19:30 et 2Sam
O Prophet, indeed We have made lawful to you your wives to whom you have given their due compensation and those your right hand possesses from what Allah has returned to you [of captives] and the daughters of your paternal uncles and the daughters of your paternal aunts and the daughters of your maternal uncles and the daughters of your maternal aunts who emigrated with you and a believing woman if she gives herself to the Prophet [and] if the Prophet wishes to marry her, [this is] only for you, excluding the [other] believers. We certainly know what We have made obligatory upon them concerning their wives and those their right hands possess, [but this is for you] in order that there will be upon you no discomfort. And ever is Allah Forgiving and Merciful. - Quran Al-Ahzab(The Confederates) 33:50 (islam)
Prohibited to you [for marriage] are your mothers, your daughters, your sisters, your father's sisters, your mother's sisters, your brother's daughters, your sister's daughters, your [milk] mothers who nursed you, your sisters through nursing, your wives' mothers, and your step-daughters under your guardianship [born] of your wives unto whom you have gone in. But if you have not gone in unto them, there is no sin upon you. And [also prohibited are] the wives of your sons who are from your [own] loins, and that you take [in marriage] two sisters simultaneously, except for what has already occurred. Indeed, Allah is ever Forgiving and Merciful. - Quran An-Nisa(The Women) 4:23 (islam)
Anyone who has sexual intercourse with a beast, a dead or living woman below the vagina, a female slave who owns some of it, or his sister who owns some of it, or his wife during her menstruation or anus, or masturbates with his hand, or a woman masturbates with a woman, shall not be subject to the hadd but shall be subject to a fine. ومن وطيء بهيمة أو امرأة ميتة أو حية فيما دون الفرج أو جارية يملك بعضها أو أخته المملوكة له اروطى، زوجته في الحيض أو الدبر أو استمنى بيده أو أنت المرأة المرأة لا حد عليه ويعزرا. - Fiqh Umdat o12.3 (islam)
Bible 2 Samuel 13:11-14 (en)Incest (4)Forced Sex (11) Ammon, son of the king David, rapes his half-sister Tamar
[11]And when she had brought them unto him to eat, he took hold of her, and said unto her, Come lie with me, my sister. [12]And she answered him, Nay, my brother, do not force me; for no such thing ought to be done in Israel: do not thou this folly. [13]And I, whither shall I cause my shame to go? and as for thee, thou shalt be as one of the fools in Israel. Now therefore, I pray thee, speak unto the king; for he will not withhold me from thee. [14]Howbeit he would not hearken unto her voice: but, being stronger than she, forced her, and lay with her. - Bible 2 Samuel 13:11-14 (bible)
Bible Genesis 19:30-36 (en)Incest (4) Lot's daughter had sex with him to give him descendants
[30]And Lot went up out of Zoar, and dwelt in the mountain, and his two daughters with him; for he feared to dwell in Zoar: and he dwelt in a cave, he and his two daughters. [31]And the firstborn said unto the younger, Our father is old, and there is not a man in the earth to come in unto us after the manner of all the earth: [32]Come, let us make our father drink wine, and we will lie with him, that we may preserve seed of our father. [33]And they made their father drink wine that night: and the firstborn went in, and lay with her father; and he perceived not when she lay down, nor when she arose. [34]And it came to pass on the morrow, that the firstborn said unto the younger, Behold, I lay yesternight with my father: let us make him drink wine this night also; and go thou in, and lie with him, that we may preserve seed of our father. [35]And they made their father drink wine that night also: and the younger arose, and lay with him; and he perceived not when she lay down, nor when she arose. [36]Thus were both the daughters of Lot with child by their father. - Bible Genesis 19:30-36 (bible torah)
Bible Genesis 38:15-18 (en)Prostitution (6)Incest (4) Tamar had tricked her father-in-law to pass as a prostitute and have sex with her
[15]When Judah saw her, he thought her to be an harlot; because she had covered her face. [16]And he turned unto her by the way, and said, Go to, I pray thee, let me come in unto thee; (for he knew not that she was his daughter in law.) And she said, What wilt thou give me, that thou mayest come in unto me? [17]And he said, I will send thee a kid from the flock. And she said, Wilt thou give me a pledge, till thou send it? [18]And he said, What pledge shall I give thee? And she said, Thy signet, and thy bracelets, and thy staff that is in thine hand. And he gave it her, and came in unto her, and she conceived by him. - Bible Genesis 38:15-18 (bible torah)