Razib Khan One-stop-shopping for all of my content

September 2, 2012

The waning of the nuclear family

Filed under: Culture,Extended Family,Family,Nuclear Family — Razib Khan @ 4:09 pm

‘The Waltons’ Meets ‘Modern Family’:

A Pew Research Center study, “The Return of the Multi-Generational Family Household,” published long before the most recent, even higher census figures, revealed that in 2008 a record 49 million Americans, or 16.1 percent of the country’s population, lived in a family household that contained at least two adult generations or a grandparent and at least one other generation.

Those figures, according to that Pew report, represented a significant trend reversal that started right after World War II. In 1940, about a quarter of the population lived in a multigenerational home (my mother-in-law, in fact, grew up sharing a house with her aunt, uncle and cousins), while in 1980, only 12 percent did.


One of the issues that occasionally crops up on this weblog is that some readers are surprised that that I would term myself conservative, since that position seems to only imply that one wishes to slow down the inexorable march toward the future. This is a particular view of progressive history, where the future always builds upon and extends the past. Another view is cyclical, or even declinist, and over the course of human history this has been a more common tendency. Instead ...

July 10, 2012

Toward healthier gestations

Filed under: Culture,Eugenics,Family,Fertility,Personal genomics,Reproductive health — Razib Khan @ 6:44 pm

Neuroskeptic has a post up, The Coming Age of Fetal Genomics:

So they don’t. Instead, they buy a $100 test kit, they each provide a small blood sample and send it off to one of the companies offering fetal genome testing. At the testing lab, they can separate out the mother’s DNA from that of the fetus, both of which are present in the mother’s blood. By comparing the fetal genome to the mother’s and father’s, it’s easy to spot de novo mutations. If a certain gene doesn’t match either the mother or the father’s sequence, it’s mutated.

A few days later the results are back. There are several mismatches detected. Most are benign – they’re not predicted to have any biological effects. But there’s one, a deletion of a few thousand bases in a gene involved in brain development. This deletion is predicted to raise the risk of epilepsy and autism from 1% to 10% apiece. The parents now have a decision to make. The mutation is a one off, it’s not inherited. If they conceive again… roll the dice again… and it’ll be gone. Do they terminate?

Like the adverts say, “Some people disagree with this, but we say there’s only one ...

February 3, 2011

Why siblings differ differently

The Pith: In this post I examine how looking at genomic data can clarify exactly how closely related siblings really are, instead of just assuming that they’re about 50% similar. I contrast this randomness among siblings to the hard & fast deterministic nature of of parent-child inheritance. Additionally, I detail how the idealized spare concepts of genetics from 100 years ago are modified by what we now know about how genes are physically organized, and, reorganized. Finally, I explain how this clarification allows us to potentially understand with greater precision the nature of inheritance of complex traits which vary within families, and across the whole population.

Humans are diploid organisms. We have two copies of each gene, inherited from each parent (the exception here is for males, who have only one X chromosome inherited from the mother, and lack many compensatory genes on the Y chromosome inherited from the father). Our own parents have two copies of each gene, one inherited from each of their parents. Therefore, one can model a grandchild from two pairs of grandparents as a mosaic of the genes of the four ancestral grandparents. But, the relationship between ...

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