User blog comment:Xilinoc/Ch. 850 - Oda's Still Got It/@comment-24442815-20161222224928/@comment-26058050-20161223001218

It's also possible that there is a significant age difference between Zepo and Pedro, OR Zepo could have had health issues in the past that reduced his life spam naturally, so the Soru Soru no Mi could also take into consideration the victims natural health. I imagine that Big Mom is the one that determines the life spam, similar to how Ivankov is able to determine which hormones to use. Speaking of which, I wonder how that's going to work with Luffy since he already lost 20 years off his life iirc from her powers. Confliction perhaps?