Why did shiho join the BO?

[Aokochan]

I know that shiho Miyano/Ai Haibara created the APTX 4869, but why did she and her sister join the Black Organization? And why did shiho wanted to create the APTX? They seem to be good persons, why would they join an organization who kills people?  ??? The same question about Shiho and Akemi's parents. Please, if you know it let me know.

[unclesporkums]

Shiho and Akemi didn't join, they were born into it, since their parents were members, they didn't have a  choice. I can only assume that their parents joined because the Organization needed their brainpower for their drug project and they were possibly blackmailed into it.

[mangaluva]

Shiho and Akemi were born into the Organization; it's heavily implied that they had no choice in their careers. As for their parents... we know so little about their true personalities and intentions that it's hard to gauge. Possibly they wanted to conduct slightly-less-than-moral research that only the BO would fund them for. Maybe they were kidnapped or blackmailed into it. Hell, maybe one of them was born into it as well and the other married in. Maybe they were BOTH born in. We just don't know.

[Kleene Onigiri]

Shiho is evil.

[ranger]

EVIL BUT CEXYYY

[Chekhov MacGuffin]

What mangaluva and unclesporkum's said is correct.
We do know from Agasa that Atsushi's theories were not well accepted in the scientific community. The Black Org could have funded Atsushi's research when no one else did because the Org and Atsushi's research interests aligned. The Org may have also provided a real sample of non-aging (Vermouth) that made it possible for Atsushi to create APTX. (Which explains why Vermouth doesn't like the research and the Miyanos and why Haibara knows Vermouth despite being in completely different divisions. Who wants to be a guinea pig?)

[Aokochan]

OK, Thank you very much for the information!!

Shiho is evil.

No, I don't think shiho is evil! She's a good and sensible person! Look at Haibara!