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In "An Introduction to Genetics" by David J. Merrell, copyright 1975 by W.W. Norton + Co., p. 742, in the Chapter "Genetic Counseling and Eugenics," the author states: "... 50% of the women produce 85% of all children born in the United States."

The author provides an Additional Reading list, but I'm not a geneticist, nor do I have access to much of the listed material. With that in mind, 1) where can one find the statistic mentioned above? and 2) has this number changed over time?

OP EDIT: In response to comment (a few examples from Reading List of 30 items):

Davis, 1970, Prospects for Genetic Intervention in Man, Science, 170 279-1283

Dubos,1965, Man Adapting, Yale Univ. Press

Dunn, 1962, Cross Currents in the History of Human Genetics, Amer. J. Human Genet, 14: 1-13

Ehrlich, 1968, The Population Bomb, Ballantine NY

...

Lynch, 1969, Dynamic Genetic Counseling for Clinicians, C. C. Thomas, Springfield, Mass.

...

Petersen, 1969, Population, 2nd Ed. Macmillan

...

1969, WHO Expert Comm. on Human Genetics, "Genetic Counselling(sic), Tech Rept 416, pp. 1-23

I know I can find stats like average ages, etc from the Statistical Abstract of the United States, but where do geneticists find items like the one cited in the Merrell book?

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  • $\begingroup$ Welcome to Biology.SE! Could please copy paste the reading list or any source that Merrell has indicated? $\endgroup$ – Remi.b Jun 30 '16 at 8:17
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    $\begingroup$ Note that it is more a question of human demography than genetics. It is still on-topic though. $\endgroup$ – Remi.b Jun 30 '16 at 8:19
  • $\begingroup$ Isn't this just an interpretation of the rate of childlessness? Say 41.2% of women don't have children. This means that the remaining 58.8% of women produce 100% of children and therefore that 50% of the women produce 85% of children. $\endgroup$ – canadianer Apr 27 '17 at 2:31
  • $\begingroup$ If a reading list is given, but it isn't clear from which book the statement is derived, it often works to google the unique aspects of the statement. If general search, which includes books, doesn't work: google scholar, with temporal filter for years prior citing work, often manage to retrieve original source $\endgroup$ – tsttst Oct 25 '17 at 4:25
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The CDC has some good stuff. http://www.cdc.gov/nchs/data/nhsr/nhsr051.pdf

But keep in mind that number from your book is likely based on yearly findings in which more than half the women would not be able to have children due to age, voluntary contraception, or other conditions. So it is not reflecting how many children they have over their lifetime. Even in the CDC study more than half the women had no children but few had no plans to have children, couples are moving their first pregnancy to later and later in life, which is going to make it look like few are having children at all on first glance. And it's probably not accounting for death rates, the poorest people tend to have the most children but they also have the fewest number live to maturity, which is why they tend to have more (not necessarily consciously mind you) .

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You can try to use some standart data sources, for example:

  1. NASA's Gridded Population of the World - LINK
  2. Geonames - LINK
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That information seems to be censored very often. In certain countries there are even laws preventing asking certain quesitons about demography, i.e. France, and In America you should have transparency for the government censors on household numbers, but apparently the official numbers discreetly use 4+, to not publish families of 8,9 and 10.

Your question doesn't say if that figure holds for 1-2-3 generations.

Big family traditions extend for more than one generation. so 5*5 becomes 25, and 2*2=4 If you square the figures, the add up very fast... Unfortunately the statistics don't measure higher than 2 children... What you need is a graph like this:

It illustrates that "4+" children actually averages about 5.5-6.5 children (vaguely)...

If your square that sum, his statistic may be true.

If you multiply the household percentage and the number of children you get a bell curve that is different:

enter image description here

The 50 percent of the women represented by the black and white graph, it seems to 3.5 children at that village, and the number of children is in the top graph, so it indeed appears that in only one generation, women with more than 3 children, for that graph, indeed produce 75 percent of the population.

Sorry that's my lame attempt to answer the question. Having checked it may help a teeny bit. it's not a sci reference though. sorry.

family size is a factor of education, professional ambition, culture, religion and ethnicity.

https://www.mtholyoke.edu/courses/rschwart/encounters/family_size.htm

http://www.pewsocialtrends.org/2015/05/07/family-size-among-mothers/

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