You owe a great deal to your parents, from the colour of your eyes to the values they teach you. But your health can be part of their legacy too, with certain genes making you more likely to develop conditions such as cancer.

Scientists are still learning about the role hereditary gene faults play in the disease, but the information we already have can give families blighted by cancer the chance to change the course of their future.

“It’s a scary thing to be told you have been born with a higher-than-average lifetime risk of cancer,” says Jo Stanford, cancer prevention officer for Ovarian Cancer Action. “But this knowledge means you are right at the front of the queue for referrals, screenings and risk reduction options.

“My mum died of ovarian cancer and I felt very helpless.

“Discovering I inherited a genetic fault allowed me to take back control and it will now be a different story for my children.”

How can cancer be in my genes?

Your genes are an instruction manual for your body so it can make proteins, the building blocks of life.

All cancers develop because something has gone wrong with one or more of the genes within a cell, leading it to divide and grow uncontrollably.

The vast majority of these faults occur due to factors such as your age or lifestyle. But a small proportion are hereditary.

“When you have a fault, it’s like having a spelling mistake in the instructions so your body can’t do its job as well,” explains Jo.

“But it’s important not to panic, as only five to 10 per cent of all cancer cases have a hereditary element.”

Ovarian, breast, prostate, pancreatic and bowel are some of the types you can be more likely to get if you carry a mutation, but the lifetime risk levels vary between cancers and carriers.

What are the gene faults?

There are two main types that we know about so far – BRCA mutation and Lynch syndrome.

All of us carry BRCA genes, otherwise known as tumour suppressors, and their job is to repair cell damage and prevent cells growing and dividing too rapidly. But some families have faults on the BRCA1 and BRCA2 genes which make them less effective.

It’s thought around one in every 400 to 800 people are carriers of these faulty genes, but this is significantly higher for people with certain backgrounds, such as Ashkenazi Jews.

The BRCA mutation has a strong link with breast and ovarian cancer but it’s just as important for men to know if they carry it as women.

Ovarian cancer can be in the genes (

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This is because it also raises the risk of prostate and pancreatic cancers, while dads can pass the fault down the generations.

Lynch syndrome is an umbrella term for mutations on a group of genes that should repair DNA damage when cells divide – MLH1, MSH2, MSH6 and PMS2.

They are most strongly linked to bowel cancer but can also increase your risk of a number of other types, including ovarian, womb and ­stomach. The prevalence of Lynch syndrome is still being investigated, but it could be as common as occurring in one in 125 people, according to the World Health Organisation.

Unfortunately, awareness of these gene faults is poor – only 25 per cent of the public have heard of BRCA, dropping to 16 per cent for Lynch, according to Ovarian Cancer Action.

More worryingly, it’s thought just five per cent of Lynch carriers know they have it, while only 16 per cent of GPs are aware of the syndrome.

How do I know if I’m a carrier?

If either of your parents has a BRCA mutation or Lynch syndrome, there is a 50 per cent chance you will too.

You only need to inherit one faulty copy to have an increased cancer risk and this can be confirmed by having a blood test. But because testing is relatively new and patchy, most of us remain unaware if these mutations are hidden in our DNA.

Looking at your family history is the best indicator of whether you should consider screening.

Jo says: “One blood relative with cancer is unlikely to be a red flag to make you eligible, but it depends on the type.

“Generally, you need to have two or three relatives with specific cancers.

“I’d recommend compiling a family tree listing any cancers and health problems on both sides.

“Next, put this information into the hereditary cancer risk tool on our website ovarian.org.uk to see whether you might meet the referral criteria.

“This also gives you a printout with the information your GP will need, and the NICE guidelines.”

Anyone referred for testing on the NHS will be able to access a genetic counsellor before and after, who can explain the process, your personal risk factors and how to tell relatives about a diagnosis.

If you’ve had bowel or womb cancer or are undergoing treatment for either, doctors should screen your tumour for signs of Lynch.

Jo recommends chasing this up if they haven’t.

Does being a carrier mean I’ll get cancer?

No. Nothing is inevitable and having the knowledge means you can take action to reduce the risks.

“Our generation are the first ones able to use this information and it is empowering to be able to do that,” explains Jo.

While people with Lynch see their lifetime risk of developing bowel cancer increase from 5.5 per cent to as much as 80 per cent, knowing you have this predisposition can be the difference between life and death.

You’ll be aware of symptoms of concern, be offered regular screenings to detect any changes and you’ll be able to make lifestyle changes to protect your health.

Bowel cancer is common among men (

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Regular colonoscopies for Lynch carriers can reduce the risk of dying of bowel cancer by 72 per cent.

There are also options for risk-reducing surgery, such as elective mastectomies and hysterectomies, while carriers without children can access a form of embryo screening that checks for BRCA mutations and Lynch on the NHS, called PGT-M.

Jo – who opted for preventative surgery when she was in her 30s – says: “These are not easy choices. It’s scary to have body parts removed, it can be lonely and it’s not the right decision for everyone.

“But for those of us who have lost a loved one to cancer, the opportunity to take back the power and say ‘this stops with me’ is wonderful.”

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