There are numerous methods to deduce age through forensic science. Summarizing them... someone even wrote a book about it, the kind that spans several hundred pages.
Basically, from teeth to finger bones to pubic bones to the six major joints to DNA and mitochondria, there's a way to infer age for all of them.
For living individuals, all imaging techniques can be used to identify age, including X-rays, CT scans, MRI, ultrasound, and so forth.
However, different approaches and locations yield different levels of error.
To pinpoint an age within a two-month range is not easy.
"The hospital or health bureau should have records, I remember helping with that, applying for a replacement birth certificate." Shen Yaowei chimed in from the side casually.
Meng Chengbiao couldn't help but glance at Shen Yaowei and chuckled, "Yaowei is good at getting things done. But for records from 20 years ago, I guess we'll need to do quite a bit of digging."