With the upcoming wedding of Prince Harry and Meghan Markle, royal weddings and lines of succession are being discussed again. This makes me wonder about lines of succession and providing heirs to the throne in a monarchy.

I vaguely recall a discussion about Kate Middleton needing to go through some type of physical examination before she could marry Prince William, but the source was not too credible. I was not sure if this was gossip or if this actually does happen.

Do heirs to a monarchy need to provide any type of proof that they can reproduce when they come of age? Do their future spouses need to go through some type of physical examination before they can marry an heir? What would happen if it was proven that they could NOT reproduce?

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    @PoloHoleSet where does the question say anything about testing infants?
    – user12754
    Commented Dec 19, 2017 at 18:54
  • @PoloHoleSet Edited to combat any confusion :) Commented Dec 19, 2017 at 19:17
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    FWIW, Roman emperors were pretty big on adoption for a period of time.
    – user4012
    Commented Dec 19, 2017 at 19:18
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    When you ask this kind of question, think that monarchy is very old. hundred years ago, there was no way to "prove fertility" except, well, giving birth. But it never stopped any monarchy to survive, because in this case the crown goes to the sibblings.
    – Distic
    Commented Dec 20, 2017 at 13:47
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    @Distic lack of suitable heirs did destroy or cripple numerous historical monarchies. But of course it's not a big deal for a constitutional monarchy. Commented Feb 17, 2020 at 20:47

2 Answers 2


The very short answer is no. The sole requirement for an heir to the throne (per the Act of Settlement 1701) is that they have to be "Heirs of [the monarch's] Body" and "such Issue to the Heirs of the Body", so basically the King/Queen's children and their subsequent offspring. There's no mention of a legal requirement for the heir or the monarch to create an heir, nor any obligation constitutionally for them to do so.

the Crown and Regall Government of the Kingdoms of England France and Ireland and the Dominions thereunto belonging should be and continue to Your Majestie and the said late Queen during the joynt Lives of Your Majesty and the said Queen and to the Survivor And that after the Decease of Your Majesty and of the said Queen the said Crown and Regall Government should be and remain to the Heirs of the Body of the said late Queen And for Default of such Issue to Her Royall Highness the Princess Ann of Denmark and the Heirs of Her Body And for Default of such Issue to the Heirs of the Body of Your Majesty

As to the spouse of the legal heir to the throne (and anyone in the top six in line to the throne), that's dealt with in the original act and clarified in the Succession to the Crown Act 2013 which indicates that the spouse needs merely to have Her Majesty's consent to marry (or otherwise their offspring aren't eligible to the throne).

A person who (when the person marries) is one of the 6 persons next in the line of succession to the Crown must obtain the consent of Her Majesty before marrying.


(3) The effect of a person’s failure to comply with subsection (1) is that the person and the person’s descendants from the marriage are disqualified from succeeding to the Crown.

The interesting test will come if/when the future spouse to the heir is a same-sex marriage, if the heir has progency as a result of sperm donation or if the heir adopts a child. None of those would result in an eligible heir (since they aren't progency of Princess Sophia) but there would be overwhelming pressure to amend the law (again) to make them eligible.

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    +1. Considering this logically: Imagine Princess Alice is next in line to the throne, but 70 years old, childless and definitely infertile. They could skip down the line of succession to her (much) younger brother, Prince Brian, who is 25 years old, unmarried, childless but presumed fertile. But what exactly does that achieve? Making Brian the King will not magically ensure that he has children to continue the royal line. Commented Dec 20, 2017 at 12:07
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    @RoyalCanadianBandit Instead of skipping past Alice, when Queen Alice dies (childless) then Prince Brian will become King anyway/eventually, and so on.
    – ChrisW
    Commented Jul 10, 2018 at 16:01

What would happen if it was proven that they could NOT reproduce?

Nothing. They would simply be unable to displace the next person in the line of succession by producing offspring. But they would retain their place in free line of succession and would ascend to the throne if the time came. For example, if Edward VIII had not abdicated and died without an heir, the monarchy would anyway have passed to his brother as it did in reality, or, if his brother had predeceased him, to the current queen.

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