First take a frog. Choose your species with care. Although the skins of some frog species produce antimicrobials, and the ability to touch for the King's Evil is a splendid certificate of true royalty, other species have remarkably poisonous skins. A prince that causes death or mass hallucinations every time he shakes hands on a royal walkabout could result in an unfortunate revolution and republicanism.

Second, put any unhygienic thoughts of kissing out of your mind. Transfection plasmids designed to transform frog to human are far too unstable to be transmitted orally, and additionally have a distressing tendency to insert randomly into the genome, resulting in a cancerous mess rather than the required princely form. An adapted version of the old-fashioned method is still considered best in this case.

Credit: JACEY

Obtain DNA from a suitable candidate. Please be careful during this step — the offspring of many royal families have bodyguards that are a little short-tempered with anyone approaching their charges with needles or syringes. It is also a bad idea to stalk the selected donor — a restraining order has never helped anyone. It is usually best to select a royal family with a number of obscure offshoots, that was deposed at some point during the twentieth century, or with a tendency for extra-pair copulation.

Remove oocytes from your selected frog. Several hundred will be required, the process still being somewhat unrefined; however, eye of newt and wing of bat are not needed, whatever the older textbooks say. As normal somatic-cell nuclear transfer methods have yet to produce viable embryos in frogs, a Transmogrifier™ kit should be used. Fortunately, this technology has recently been adapted to be used with microinjection equipment. One potential disadvantage of this method is that significant amounts of the original oocyte DNA can recombine with your candidate DNA. Do not worry about this too much — royal offspring with a fondness for flies can do little harm. If the Emperor of Japan can be an expert in guppy taxonomy and the occupier of the throne of Great Britain and the Commonwealth talks to plants, a royal entomologist is not going to raise any eyebrows.

Incubate the cells as usual, then implant them into a surrogate mother. With an amphibian–mammal cross such as this, it is generally considered that a marsupial surrogate is the best compromise, particularly considering the superb nutritional quality of the milk provided once your clutch of princes has hatched.

Once you are assured of at least one healthy male child, social exposure becomes of primary importance. You must send the hatchlings to a school, the older the institution the better. Although it may appear irrational to put a not-entirely-human creature through a further de-humanizing experience, it does ensure that any of his remaining quirks and foibles that have not been crushed out can be laid squarely at the door of his educational facility. The ability to ride a horse and to dance are the two most common abilities required by ruling families, so concentrate on these. You will probably have to pay extra for this tuition. Fortunately the ability to slay dragons is no longer required. All dragons hatched to date have, by EU legislation, been toothless, flameless and survive solely on blood-agar soup. This is probably for the best as the training for this skill is notorious for reducing the number of viable princes available.

Once the growth period and education are over, you can now habituate your specimen to its natural habitat. This is where choosing the DNA of an obscure royal family is of benefit, particularly if they have a tendency to extra-pair copulations. The most basic of unsubstantiated stories will be more than enough, when supported with your specimen's DNA fingerprint and phenotype (a good strong phenotype, such as the Bourbon nose or the Hapsburg lip, is also a good idea).

Unfortunately by this stage, unless you have modified your own telomeres, you will be far too old to be a suitable mate for your prince, as it is well known that princes require mates as least ten years their junior in virtually all societies. If you have planned for this, you will have imprinted your prince at an early age with either a scent or sound that will require him to marry a woman of your choosing, preferably your daughter for kin-selection and socio-political control purposes.

However, be careful as this leaves you in a rather precarious position — you will be the type of mother-in-law that has the power to change frogs into princes or princes into frogs. They have a tendency to come to a bad end. Make sure to keep your distance from open oven doors, ducking stools and stakes in the centre of pyres of wood that will inevitably appear whenever you visit.