At present, there is a saying circulating on the Internet that the eyes of the Manchus are brown, is this statement reasonable? Personally, I think that this problem can be analyzed from two perspectives:
The Manchus came
As a biological father and son, there is still a phenomenon of genetic variation - that is, the child is not like his father or mother in many ways, and it is undoubtedly anti-science to expect a nation to share common biological characteristics.
So both from a sociological point of view and from a biological point of view
In terms of degree, nationality is a relatively virtual concept, and this problem can be said from the Manchus.
In contemporary times, the mention of manchus often involves the relationship between the Jurchens of the Jin Dynasty and the Jurchens of the Ming Dynasty. In fact, the Jurchens of the Jin Dynasty in the Central Plains (such as the descendants of Jin Wushu), whether in the 21st century today or in the Qing Dynasty, belong to the category of Han Chinese, but when it comes to blood, this part of the Jurchens is regarded as the purest and most authentic Jurchen of the bloodline, and from this point of view, it is not difficult to see that what determines the composition of a nation is not only related to blood, but also involves identity.
In the last year of the Ming Dynasty, emperor Taiji of the Later Jin Dynasty carried out a series of reforms for the Later Jin Khanate in order to replace the decaying and dying Ming Dynasty. This includes changing the name of the country and changing the name of the clan - changing the Jin to the Qing Dynasty, and changing the Jurchen to Manchuria.
In the reform of Huang Taiji, the composition of the Manchus (Manchus) also changed: in addition to the Jurchens outside Guanwai, some Mongols, Koreans, and even Han Chinese in the Later Jin Dynasty were also included in the Manchu sequence.
After the Qing Dynasty entered the customs, many Han people, in order to elevate their status, would exchange their status as flag people for themselves through various means, such as battle achievements and even bribery.
After the founding of New China, many Mongolian bannermen and Han flagmen were included in the Manchu category, but the Orunchun, Dahuoer people, who were regarded as having a deep relationship with the Manchus, and the Hezhe people were not included in the Manchus.
This shows that the Manchus are actually a historical and cultural nation, not a blood nation. Since it is not a bloodline nation, how can there be any biological commonality of brown eyeballs?
Biological perspective
Biologically, what color a person's eyeball is depends on the color of their iris. How color the iris appears depends on the number of pigment cells in a person's iris - if there are more pigment cells in a person's iris, its eyeballs will appear black, and if the pigment is relatively small, it will show the color of brown or even amber.
The number of pigment cells depends on the genetic factors of the individual, and it is not universal in any ethnic group, so whether it is Manchus or Han Chinese, there will be groups with brown eyeballs.