Not sure if someone already said it but do you remember when Sanji was afraid of moths and spiders at Jaya ? Notice the moth's wings and the design of his sister’s cape…
https://66.media.tumblr.com/6c4962770aaf0869580c27440d35fe25/tumblr_o7hfk8kHEZ1sqzg6to1_400.jpg https://65.media.tumblr.com/70eda155bd5c3f9d3e429497038b2ba4/tumblr_o7hfk8kHEZ1sqzg6to2_400.jpg
Maybe his older sister is the one who taught him never to hit a lady.
Trough not so kind methods…