The Compendium of Caraka 4.2.20

4.2.20

māturvyavāyapratighena vakrī syādbījadaurbalyatayā pituśca/
īrṣyābhibhūtāvapi mandaharṣā-vīrṣyāratereva vadanti hetum//

From obstruction of the mother’s intercourse and from weakness of the father's seed, one becomes deformed; / when both are overcome by jealousy and have sluggish arousal, they state this as the cause of taking pleasure through jealousy.