At what age ....

[edison]

Based on what we did with our kids (youngest is approaching 12), I'd say about 8 years old.

More importantly, I now say my own age is forty twelve...

[NotAllThere]

That answer needs a graph

Not really. Anyway the figures are:

Age	6months
---	-------
1	50.0%
2	25.0%
3	16.7%
4	12.5%
5	10.0%
6	8.3%
7	7.1%
8	6.3%
9	5.6%
10	5.0%
11	4.5%
12	4.2%
13	3.8%
14	3.6%
15	3.3%
16	3.1%
17	2.9%
18	2.8%
19	2.6%
20	2.5%

So probably you're look at 4%. 13 and a half is pushing it, but 12 and half I can imagine kinds saying.

[hugebrain]

Not really. Anyway the figures are:

Age	6months
---	-------
1	50.0%
2	25.0%
3	16.7%
4	12.5%
5	10.0%
6	8.3%
7	7.1%
8	6.3%
9	5.6%
10	5.0%
11	4.5%
12	4.2%
13	3.8%
14	3.6%
15	3.3%
16	3.1%
17	2.9%
18	2.8%
19	2.6%
20	2.5%

So probably you're look at 4%. 13 and a half is pushing it, but 12 and half I can imagine kinds saying.

Obvious fail.

Should be one and a half, two and a half etc. on the left. Otherwise the question doesn’t even come up.