I tried in Bard just for comparison's sake and it got to 1 while still saying a different number. It's a bit strange, here:

Julia has two sisters!

Here's the reasoning:

1. *Julia's brothers have sisters*: Each of Julia's three brothers has two sisters. This means in total, her brothers have 3 brothers * 2 sisters/brother = 6 sisters.

2. *Those sisters are not additional*: However, it's important to remember that these sisters belong to Julia's brothers, not directly to Julia herself. Julia and her sisters are siblings, not counted among the sisters her brothers have.

3. *Therefore*: Julia has 2 sisters (herself and one other).

So, while Julia's brothers have a total of 6 sisters, only Julia and one other sister are Julia's own sisters.

.

It’s way more complicated. As an example, my kid has one half sister and had one step sister. My kid referred to both of them as their sisters, but the step person didn’t acknowledge my kid as such.

Even if we err on the side of the step, take the half sister entirely out of the equation and only focus on the step relationship, one would have claimed 0 sisters and the other would have claimed 1. They were talking about each other and they were both telling their truth. But the answer is simultaneously 0 and 1.

It gets even more interesting because neither my kid nor their step sibling are cisgender. I don’t know what to call their step so just use their name and pronouns now. The step still won’t acknowledge they’re siblings and I respect that a lot.

When these smart young folks take over, the world will get really cool.

Edit - This was way more complicated to explain than I anticipated.