Is it permissible to marry a person with curly hair?

The competency (Kafa'ah) of a man for a woman in marriage is considered by the majority of scholars, though its definition varies. Some stipulate six matters: lineage, religiosity, attribute, freedom, freedom from defects, and financial ability. Others suffice with fewer.

Marriage is not permissible unless there is competency in religion. Thus, it is not permissible for a Muslim woman to marry a non-Muslim. As for matters other than religion, the majority of scholars say that competency is a right for the woman and her guardians. If they waive this right, it is permissible. They cite as evidence the story of the marriage of Fatima bint Qays al-Qurashiyah to Usama ibn Zayd, the freed slave, by order of the Prophet, peace and blessings be upon him.

If the woman and her guardians consent to marriage with someone who is less competent in matters other than religion, there is no harm in that. It is recommended to marry someone whose religiosity and character you are pleased with.

As for the phrase "lineage is treacherous" (al-irq dassas), it appeared in weak hadiths. However, it is reported in Sahih al-Bukhari and Muslim that resemblance may draw a newborn towards one of his ancestors, as in the hadith of the man to whom a black boy was born, whereupon the Prophet, peace and blessings be upon him, said: "Perhaps this son of yours was drawn [in resemblance] by a lineage."