[yuzen003]

Originally Posted by cyberdemon

they say so in the new chapter posted today

Untouchable — The Nightmare of 2062?

Is this the section talking about it?

Spoiler for Is this the relavent quote?:

The research focus of the Fourth Institute that birthed the Yotsuba clan was "the endowment and improvement of magical abilities given by the mind's structure for the usage of mind manipulation magic." In order to fulfill this purpose, The Fourth Institute first gathered people whose lineage predisposed them to have mind manipulation power.

Among these people, some individuals were transformed into genuine super powered beings, while others remained no more than mere illusionist tricksters who could do no more than create heat haze like mirages. The magicians with strong mind manipulation abilities were picked out, strengthened, and had the primary field of their magic calculation area directly modified. That was the Fourth Institute's accepted procedure for magician development.

Everything is in the past tense so I interpreted that as the experiments were done by the Fourth Institute and the Yotsuba were the end result, not that they continued after creating the Yotsuba bloodline. The test subjects before they were officially Yotsuba and founding members might have been experimented on, but the succeeding generations who officially were Yotsuba would have been strong magicians so there would have been less necessity to risk them.