I always thought they were related just based on how similar they look:
Tuka:
http://www.cazin.net/sport/vijest/uspjeh-karijere-amel-tuka-pobjednik-utrke-na-800-metara-u-monacu
Casey:
http://dailyrelay.com/5-questions-pat-casey/
Anyway, here's the link confirming what we already all suspected: