Genetics has come a long way since Mendel messed with pea plants in a monastery garden, but it still has a way to go. Though we’ve sequenced the human genome and identified a number of disorders that come straight from crippled or misread DNA, we are still chasing the dream of personalized, genomic medicine.

But in rare cases, we know exactly what a defective gene means. And when Angelina Jolie learned about her own genetic predisposition to breast cancer – and made her diagnosis and treatment very public – she unknowingly urged thousands of women to follow her lead.

“BRCA 1” and “BRCA 2” denote two genes in our DNA that produce tumor-suppressing proteins. When BRCA 1/2 mutate in a specific way, that suppression can fail, leading to an increased risk of breast and ovarian cancers. These mutations account for a quarter of inheritable breast cancers (themselves five to ten percent of all breast cancers). A woman who has a mutation in either gene has a greatly increased risk of getting breast cancer sometime during her life — much greater than the general population.

When Angelina Jolie was screened for the BRCA mutations, her doctors told her she had an 87 percent chance of getting breast cancer during her lifetime. In the face of that knowledge, Jolie acted, and chose to have a double mastectomy. The announcement of her surgery was maybe more galvanizing than any recent pink-tinted campaign.

“The Angelina Jolie Effect has been long lasting and global,” says a new study appearing in the journal Breast Cancer Research. The team of researchers, lead by Dr. Gareth Evans, professor of clinical genetics at Genesis Breast Cancer Prevention in the UK, found that between 2012 and 2013 – the time frame before and after Jolie’s announcement – breast cancer referrals almost tripled for women in the UK (from 1,981 to 4,847 referrals). Evans looked at 12 family history clinics and 9 genetic centers in the UK for the data.

Genetic screening requests for the BRCA 1/2 mutation also doubled over the same period, and the inquiries about mastectomies significantly increased.

Of course, correlation does not prove causation. It’s possible that Jolie’s announcement simply happened at the same time that women were seeking more screenings and referrals. But, as the BBC points out, similar trends have appeared before, as “attendance for cervical cancer screening rose in 2008 and 2009, when the celebrity Jade Goody was diagnosed with cervical cancer and died.”

And Jolie’s reveal may have had more impact than it otherwise would have for a celebrity. “Angelina Jolie…is likely to have had a bigger impact than other celebrity announcements, possibly due to her image as a glamorous and strong woman,” Evans said in a press release.

“This may have lessened patients’ fears about a loss of sexual identity and encouraged those who had not previously engaged with health services to consider genetic testing.”

Is “The Angelina Jolie Effect” a good thing? On its face, it would seem like encouraging women to get screened for a particularly dangerous mutation is a good thing. And the study found that there wasn’t an increase in “inappropriate” screening referrals. However, handling risk is, well, risky.

About 12 percent of women will develop breast cancer sometime in their lives. Of these women, 5 to 10 percent of them will develop a hereditary breast cancer. And of those cancers, one quarter will be linked to either mutated BRCA gene. Though Jolie brought her mutation out of the genome and into the limelight, the percentage of women potentially in Jolie’s is much smaller than you might expect. Not only that, but the number of women for whom a double mastectomy is a sensible treatment – medications and lifestyle changes are other, viable options – is even smaller. This isn’t to say that women shouldn’t bother getting screened for the BRCA mutations, but there is a trade-off, and that trade off is for peace of mind.

The National Cancer Institute shares these considerations. “Most experts agree that mutation testing should be performed only when the person’s family history suggests the possible presence of a harmful mutation in BRCA1 or BRCA2,” states the Institute’s BRCA page. When women think a cancer is more common than it actually is, the harm comes not from ignorance, but from unnecessary stress, fear, biopsies, and medications.

What is the responsibility that a world-renowned celebrity must take on when giving medical advice? To her credit, Jolie’s statement in The New York Times acknowledged both that the BRCA mutations are rare and that if you have a family history of breast or ovarian cancer, perhaps you should get screened as she did. But whether intended of not, it seems that many women took Jolie’s experience as their own (at least in the UK), and flocked to centers to lay out their own genetics.

The Angelina Effect then, is complicated and conditional, informative yet perilous.

“While a woman’s risk of developing breast cancer and/or ovarian cancer is greatly increased if she carries the harmful mutation of the BRCA1 or BRCA2 gene,” Lester Barr, chairman of Genesis Breast Cancer Prevention, told the BBC, “preventative surgery is by no means the answer for everyone.”

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Kyle Hill the Chief Science Officer of the Nerdist enterprise. Follow on Twitter @Sci_Phile.