IF your IQ isn't up to brain surgery or a Nobel Prize, blame your ageing dad.
Intellectual whizzes（やり手、達人）, on the other hand, can thank their older mums.
The surprising conclusions come from an Australian and
In their study of 17,148 boys born in the US between 1959 and 1965, they found that children conceived （受胎する）by older fathers performed less well on a range of thinking tests given at eight months, four years and seven years than those born to younger dads.
They took into account （～を考慮に入れる）other possible factors such as education, mental health and income, with the same result.
"While we didn't find a clean threshold（分かれ目） above or below which there is a risk (of lower IQ), the risk increased steadily the older the dads were," Professor McGrath said yesterday.
Writing in the
According to Professor McGrath and his colleagues, the difference may lie in the male and female reproductive（生殖の） systems. A woman is born with a fixed number of eggs that have undergone 22 cell divisions in the womb. But sperm cells divide every 16 days after a boy reaches puberty（思春期）. By age 20, the original sperm cells have divided roughly 150 times; by age 50, 840 times. The more cell divisions, the more mutations（突然変異）; the more mutations, the greater the chance a child will be born with physical or neurological abnormalities.
Until recently, studies of the risks of later conception focused on women. It's well known, for instance, that as women age, the likelihood increases of their having a child with the developmental and intellectual disorder Down syndrome.
In a review of the team's paper, also in PLOS Medicine, psychiatrist Mary Cannon of the Royal College of Surgeons in Ireland wrote that evidence was accumulating that advanced paternal age was a risk factor for neuropsychiatric conditions such as schizophrenia and autism, as well as physical problems such as cleft lip and palate, childhood cancers and congenital （生まれつきの）heart defects.
"The body of evidence implicating paternal age as a risk factor for a range of adverse（not favorable） offspring outcomes should not be ignored," she concluded.
To tease out （（情報）を得る）precisely why older dads sire（〈子〉を作る） youngsters with IQ scores up to three points lower than younger fathers, Professor McGrath's group has begun investigating a group of 7000 babies born in Brisbane in the 1980s.
They are also studying the phenomenon in mice to identify the mechanism or mechanisms involved.
"Age is something to factor in （～を含めて考慮する）when planning a family," Professor McGrath said.
(543 words)
From The Australian online
Total articles :2
Total words :1743 words
＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊
知的な子供をもつのに越したことはないけれど
年取ってから子供を持つのは大変そう（＾＾；）
それにしてもこのolder mumって
何歳ぐらいのママを示唆してるんでしょうかね！？
３０の私は
もうこのolder mumの範囲に入ってるのかしら（＾＾；）
（・・子供いないけど、ってか結婚すらまだだし。。。（＾＾；））
今流行のクーガーカップル（中年女性と若い男性のカップル）だと
スンバらしい子供が生まれる、、のかなぁ～。
