You can find out about inheritance laws in 1800 England by going to a law library. Law libraries have archives of all the laws passed each year.
Downing Professor of the Laws of England was created in 1800.
There is no known "inventor" of the laws of biological inheritance, like other laws of nature, they were discovered. Mendel is the person you are most likely looking for. For more information, look up Mendelian Laws of Inheritance.
You are not a legal heir-at-law of your in-laws. Your spouse is related to them by blood but you are not. You can check the laws of intestate succession in your state at the related question link below.
finders keepers
Laws of inheritance evolved from ancient common law that was eventually codified in modern state probate codes.
Laws about inheritance vary depending on the country, so check the laws for your specific country. But in general, it should be possible to decline an inheritance - and sometimes it may be to your advantage to decline it, because receiving the inheritance may come along with certain obligations - such as taxes paid on the inheritance, or conditions imposed by the person who leaves you the inheritance.
Gregor Mendel
No. Property that you receive by a will IS an inheritance. Property received from a relative under the laws of intestacy when there was no will is also an inheritance.
A legally adopted child has all the rights of a biological child for purposes of inheritance under the state laws of inheritance and intestacy.
The law of inheritance in Islam was revealed during the time of the Prophet Muhammad, through verses in the Quran. It outlines rules on how an individual's wealth and property should be distributed among heirs upon their death. The laws of inheritance are considered an important aspect of Islamic jurisprudence.
A spouse does not have any right to a mother in laws inheritance unless they are named specifically in the ill. You could contest the will with an attorney but you probably wouldn't win.
Inheritance laws vary by location, but generally, a spouse may not have automatic rights to inherit from their in-laws. In most cases, the inheritance goes to the deceased's children or other direct descendants first. It's essential to consult with a legal professional to understand the specific laws and rights in your area.