In the early morning of the 14th, Wang Baobao released a blockbuster news on Weibo.

To release this kind of news in the early hours of the weekend, media friends who have to work overtime to catch up on the manuscript are very upset.

Because everyone knows that revelations in the entertainment industry often take surprising turns, so you must continue to pay attention to things as soon as they come out. Sure enough, some media later claimed that Wang Baoqiang was raising three female college students, but it didn't take long for it to be proven to be a rumor.

Later, the media broke the news that Wang Baoqiang conducted a paternity test for his two children and found that "the DNA similarity was only 2 to 8 percent."

Tadpole, who is committed to using all hot topics to popularize science, is suffering from no entry point, so the rumormongers come to visit!

Warm up: Beijing Second Hospital confirmed?

Doing forensic appraisal requires corresponding qualifications. Does Beijing Second Hospital have one? We can log on to the official website of the Beijing Municipal Bureau of Justice (/) to view it.

There is an inquiry service on the homepage of the official website

After inquiry, this hospital does not have the qualification for forensic appraisal.

The highlight: DNA similarity 2%~8%?

Isn’t it said that the genetic similarity between humans and chimpanzees is still 96%? What the heck is it that the DNA similarity is only in single digits? Could it be that Baby Wang, who makes us feel so distressed, is actually an alien?

To find out what the paternity test is, we first need to invite a familiar stranger-Mendel.

(Yes, this is my high school biology teacher’s PPT. The pictures that follow are almost all in this style. ps, students in the last row, please listen carefully.)

(Knock on the blackboard)

Although they are both peas, they look very different because they have different traits.

Similarly, although we are all human beings, we have many differences, such as flat tongue/rolled tongue, straight/curved fingers, whether there are dimples, etc.

Facial control people must be thinking about which one looks better, but Mendel was thinking about it.

After a series of experiments (that is, what you scumbag students will never understand) Part), he finally discovered the so-called "genetic factors", which we call genes.

A person has a pair of alleles, one from the father and one from the mother. The man who needs to determine whether he has a paternity relationship with the child is called the controversial father, or presumed father, or alleged father (AF), or AF for short, in forensic medicine.

After understanding these terms, we can briefly understand the principles of paternity testing through a picture.

On the left, the child’s genotype is OO, and AF’s gene does not contain O, so AF is not the child’s biological father. On the right, the child's genotype is OO, and AF's gene contains OO, so AF may be the child's biological father (Source: "Forensic Evidence")

From this we find that the basics of genetic identification The principle is that it can only be ruled out, not confirmed. In other words, if Baobao Wang really goes for a paternity test, it will be easy to prove that he is not the biological father of the child, but it will be difficult to prove that someone is the biological father of the child.

Therefore, in actual operation,

“The cumulative exclusion probability of genetic markers used in experiments should be equal to or greater than 0.9999. In order to avoid potential mutation effects, it is not possible to rely solely on one genetic marker under any circumstances. If the marker does not conform to the genetic law, the paternity index is calculated as needed, including the paternity index of all individual genetic markers, and the cumulative paternity index is calculated.

——"Forensic Forensic Science"

Now we know that the probability is 0.9999 instead of 1, which is prepared for genetic mutations. When the probability does not reach 0.9999, new genetic markers must be continuously detected until it reaches 0.9999. Otherwise, if the result is 2% to 8%, it means it is still uncertain. Isn’t this paternity test in vain?