Will she incur sin or punishment for refusing to marry a man who is disabled, whose illness is hereditary, and likely to be passed on to children?

A woman is not religiously obligated to accept a suitor if she is not pleased, even if he has no defects, and she incurs no sin by refusing. The Prophet, peace be upon him, commanded accepting a suitable match in marriage as a recommendation, not an obligation: "If there comes to you one whose character and religious commitment you approve, then marry him. If you do not do so, there will be tribulation on earth and widespread corruption." Islamic law warns against establishing relationships with foreign men without legal boundaries, due to the great harms involved therein.