Say the initial clan consisted of 25 couples, aged 1, 2, 3, ... to 25 years old. And people die after 25 years. And each couple between 18 and 25 years have one

Say the initial clan consisted of 25 couples, aged 1, 2, 3, ... to 25 years old. And people die after 25 years. And each couple between 18 and 25 years have one baby per year. Then the population will quadruple in less than 25 years. That's more than 5% population growth. So, people dying of old age does not limit population growth rate to less than 2%.