Making a Will is not about wealth it is about making sure that what you want to happen to your estate does happen. It gives you the opportunity to specify such things as who will administer your estate, who will care for your children and who will receive specific items of your property.
At one time illegitimate children did not inherit under a gift 'to my children.' It is not proposed to go over the old rules in this website but to refer briefly to the two statutes which replaced the old rules.
For wills made between 1st January 2000 and 4th April 1988 the position is governed by The Family Law Reform Act 1969.
As a result of that Act any reference, express or implied, to a child of any person must be construed as including a reference to any illegitimate child. Likewise, any reference to a person related in some manner to another person must be read as if he or another person through whom the relationship is deduced had been born legitimate. In both these circumstances a contrary intention may be expressed in the will.
There are two points to note here. Firstly, that the Act refers to dispositions specifically. The result is that a gift to 'my children' would include illegitimate children but an appointment of 'my children' as executors would not because the appointment of executors is not a disposition.
Secondly, the Act specifically stated that construction of the word 'heir' was unaffected.
The Family Law Reform Act 1987 replaced the provisions set out in the 1969 Act. The result is that in wills made after 4th April 1988 any reference to a relationship between two people is construed without any regard to notions of legitimacy or otherwise. The Act also extended the provisions to include the word 'heir'.
Note that for wills made after 1st January 2000 and before 4th April 1988 the 1969 Act still applies.