What is the record number of generations alive at the same time?

[Rand]

I'll go with 10. Consider a scenario where each generation had their first child at age 12, which is roughly the age a female can start giving birth. In order for an eleventh generation to realistically be alive at the same time as the oldest ancestor, the oldest ancestor must live to age 120 or the youngest descendent must give birth at a disgustingly young age. More disgusting than 12, in fact.

108 - Great, Great, Great, Great, Great, Great, Great Grandmother
  96 - Great, Great, Great, Great, Great, Great Grandmother
  84 - Great, Great, Great, Great, Great Grandmother
  72 - Great, Great, Great, Great Grandmother
  60 - Great, Great, Great Grandmother
  48 - Great, Great Grandmother
  36 - Great Grandmother
  24 - Grandmother
  12 - Mother
    0 - Baby

[Rand]

I'll go with 10. Consider a scenario where each generation had their first child at age 12, which is roughly the age a female can start giving birth. In order for an eleventh generation to realistically be alive at the same time as the oldest ancestor, the oldest ancestor must live to age 120 or the youngest descendent must give birth at a disgustingly young age. More disgusting than 12, in fact.

108 - Great, Great, Great, Great, Great, Great, Great Grandmother
  96 - Great, Great, Great, Great, Great, Great Grandmother
  84 - Great, Great, Great, Great, Great Grandmother
  72 - Great, Great, Great, Great Grandmother
  60 - Great, Great, Great Grandmother
  48 - Great, Great Grandmother
  36 - Great Grandmother
  24 - Grandmother
  12 - Mother
    0 - Baby

Safe to say 10 is not possible

Like, usually teenage pregnancies happen more often in third world countries or families that are poorer. Life standards would be lower.

You don't just require the 108 year old to be still alive, but also all the ones below her (for them to be alive at the same time).

Given 108 is already exceptionally unique and puts you into contention for oldest person in my country to be alive, safe to say this hasn't happened.

8 or 9 i guess are possible

Likely 7

I personally don't know a lot of people who even have 4. Like my grandmother died earlier this year, none of her grandchildren had babies already.

12 is also assuming each person had a teenage pregnancy, i think 16 or 18 are safer to test out

0
18
36
54
72
90
106

This brings you to 5-6

0
16
32
48
64
80
96

This brings you to 6

I think 6 is already very rare, and again, they all have to be still alive at the same time, just not the oldest person.

7 probably has happened i think, but i don't believe 8 has.

Wrong.