Your parents want you and your sister to both adopt their lifestyle.
No desire to earn an honest living that pays the bills or obtain any employment, complete welfare dependency, unemployed women with no regular monthly earnings or much in savings choosing to have children that are fed & housed by the taxpayer funded welfare state and raising them to follow the very same lifestyle.
Put your own ambitions and health first.
Your parents & sister have just as much right to choose their own ambitions and lifestyles as you do.
Your parents may well reach retirement age and be eligible for a full state pension or disability benefits having never earned a penny or applied for any paid employment.
But it is very unlikely that your sister will be able to do so, regardless of how many children she will have or how entitled she feels to living off her partner's income and any welfare funds that she receives.
The eligibility requirements for the state pension have changed a lot since your parents started claiming welfare and it is likely that some new austerity measures will be introduced to restrict the numbers of short to medium term claimants entitled welfare support.
Most healthy welfare claimants without criminal records are required to apply for some paid employment in order to avoid losing some/all of their monthly welfare cash.
Don't allow the insults or unsolicited advice of any jobless jerk to discourage you from earning a living, studying and working towards building the happy future life that you want.
Good luck!