User blog comment:B214/General Discussion/@comment-4547267-20160814221628

After some thinking, i came to a conclusion, the possible reason that Koneko and Kurako future kids were possible born around the same time could be mating season. Think about it, Koneko almost mated with Issei because it was the season and she loves him, but Kurako stopped her. However maybe in the future Kurako fell in love with Issei and both of the sister 'attacked' Issei during the season!