The prohibition that results from breastfeeding is related to the issue of the male
وَحَدَّثَنَا أَبُو بَكْرِ بْنُ أَبِي شَيْبَةَ، وَأَبُو كُرَيْبٍ قَالاَ حَدَّثَنَا ابْنُ نُمَيْرٍ، عَنْ هِشَامٍ، عَنْ أَبِيهِ، عَنْ عَائِشَةَ، قَالَتْ جَاءَ عَمِّي مِنَ الرَّضَاعَةِ يَسْتَأْذِنُ عَلَىَّ فَأَبَيْتُ أَنْ آذَنَ لَهُ حَتَّى أَسْتَأْمِرَ رَسُولَ اللَّهِ صلى الله عليه وسلم فَلَمَّا جَاءَ رَسُولُ اللَّهِ صلى الله عليه وسلم قُلْتُ إِنَّ عَمِّي مِنَ الرَّضَاعَةِ اسْتَأْذَنَ عَلَىَّ فَأَبَيْتُ أَنْ آذَنَ لَهُ . فَقَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم " فَلْيَلِجْ عَلَيْكِ عَمُّكِ " . قُلْتُ إِنَّمَا أَرْضَعَتْنِي الْمَرْأَةُ وَلَمْ يُرْضِعْنِي الرَّجُلُ قَالَ " إِنَّهُ عَمُّكِ فَلْيَلِجْ عَلَيْكِ " .
'A'isha (Allah be pleased with her) reported: My foster uncle came to me and sought permission (to enter the house), but I refused him permission until I had solicited the opinion of Allah's Messenger (ﷺ). When Allah's Messenger (ﷺ) came, I said to him: My foster-uncle sought my permission to (enter the house), but I did not permit him, whereupon Allah's Messenger (ﷺ) said: You better admit your uncle (into the house). I ('A'isha) said: It was the woman who suckled me and not the man. (But he) said: He is your uncle, admit him.